ACRONIS AND THE QUANTUM COMPUTER

BY ALEXEY KAVOKIN

MOSCOW 2020 CONTENTS

4 Chapter 1. The girls’ college 74 Chapter 16. A quantum computer

10 Chapter 2. Acronis on the phone 80 Chapter 17. The school hacker

14 Chapter 3. Adventures on Hyperbola road 86 Chapter 18. Doughnut

18 Chapter 4. Chatting under the bed 92 Chapter 19. A charity walk

22 Chapter 5. The mystery of “Enigma” 98 Chapter 20. The bulldozer

26 Chapter 6. Encryptions and codes 102 Chapter 21. Aruk Matan

32 Chapter 7. The duel 106 Chapter 22. Quantum measurement

36 Chapter 8. The liquid light 110 Chapter 23. In the tower

42 Chapter 9. Over a glass of Pimm’s 116 Chapter 24. The chase

46 Chapter 10. A music lesson 120 Chapter 25. The hospital

50 Chapter 11. The Turing Bombe 126 Chapter 26. A wave function

56 Chapter 12. The trap 134 Chapter 27. Visiting Shelly

60 Chapter 13. Sergeant Barrow 138 Chapter 28. Encrypted letters

64 Chapter 14. The telegraph code 142 Chapter 29. The School Ball

70 Chapter 15. Marie-Rose birthday party

3 CHAPTER 1 THE GIRLS’ COLLEGE

A dark-blue Land Rover pulled up outside an ancient, ivy-covered building and parked awkwardly across the pavement. A skinny 12-year-old girl with two reddish plaits jumped out of its left front door. The girl’s dad, who was rather plump, also got out of the car from the driver’s side. Together, they opened the boot and pulled out a huge sports bag. The man dragged the bag onto the porch of the mansion and stopped to take a breath. His daughter, meanwhile, was already knocking on the oak door with a copper door knocker hanging on a chain. The door opened slightly and a friendly young lady appeared. The man took a deep breath to introduce himself, but his daughter was quicker: “Good afternoon! I’m Acronis. This is my dad.” “Oh, Acronis! We’ve been waiting for you!” the young lady exclaimed. “Come in, hurry up!” Then, addressing the girl’s dad, she said: “Good afternoon, Sir. My name is Amanda Parfitt. I’m Housemistress at Finley College, where Acronis will be staying. You must be tired. Would you like some tea?” Acronis’ dad happily agreed and the three of them went into the sitting-room. While Miss Parfitt was making tea, Dad whispered to Acronis: “You haven’t changed your mind, have you, my dear?” “Of course not, Dad,” the girl declared firmly. “What about you and Mum? Are you still going to divorce?”

5 “You see, Sweetheart,” Dad looked a bit embarrassed, “As you probably know, your mum is the one to make decisions in our family.” “And you are the one to blame!” pointed out Acronis. At this moment, Miss Parfitt stepped into the room. She was holding a round tray with a porcelain teapot, a bowl of sugar, a milk jug and three cups on it. A nice chat over tea turned out to be a real torture for Acronis’ dad. He seemed so uncomfortable talking about school issues that he confused lacrosse with netball and said that Acronis was able to solve quadratic equations. Pretending she was carefully studying a golden cup standing on the fireplace, the girl nudged her

dad with her elbow. ICTIONARY

Finally, Miss Parfitt suggested they should go upstairs and check out the room where Acronis was D going to stay. Dad lifted the heavy bag and followed Miss Parfitt and Acronis, who were discussing the school timetable for the next week in quite a business-like manner. On the way he stopped at the upstairs landing. His attention was drawn to a glass case with a half-open box made of dark wood. There was a metal device in the box. It looked like an old typewriter with some switches above the keyboard, a set of rotating disks and a row of round lights. Written on it was: “The Enigma-M3­­ encryption device, seized on May 9, 1941 onboard of the U‑110 submarine. Property of the National Computer Museum, Bletchley Park.” Meanwhile Acronis had already chosen a bed in the spacious, but quite basic room where she was going to live. “You can go now, Dad,” said Acronis, as soon as her father dragged her bag into the room. “I’ll sort it out.” “When are your roommates going to be back?” Dad asked, looking at the seven other identical beds in the room. The Enigma machine “I have no idea! I know that everybody has to be at church by 7.30 p. m.,” Acronis explained. Is an electro-mechanical cryptographic device used by the Germans in the Second “What about dinner?” Dad looked worried. World War. It worked as a typewriter. The cryptographer typed the text using “At 6.30. And, please, don’t forget that I’m only allowed to use my phone from 8.00 to 8.30 the keyboard. When a key was pressed, the rotating disks of the Enigma machine transformed the text in a special way, changing it into a code. Although the device every evening.” was considered to be absolutely secure, British experts from the secret laboratory “That’s great! I’ll call you at 8.00 sharp.” of Bletchley Park managed to create a machine capable of decoding its messages. “No, you won’t!” Acronis cut him off. “I’ll call you myself after I’ve talked to Mum.” It was called the Turing Bombe. Dad sighed and headed to the exit. When saying goodbye to Miss Parfitt, he couldn’t help asking: “How come you have the Enigma encryption device in your school?”

6 “We need it for one of the projects,” Miss Parfitt explained. “Our Physics teacher, Miss Holly, borrowed it from the Computer Museum for the spring term. One of the girls is going to do a project on cryptography.” “How interesting!” He was impressed. “Yes, it is! See you next time,” said Miss Parfitt. Dad went down the stairs, got in the car and cast a sad look at the school door closing behind him. He didn’t like the idea of leaving Acronis in the boarding school for girls. But there was no going back. The choice had been made already. ICTIONARY

ψ D

Lacrosse and netball Are group games included in the physical education curriculum for girls in many English schools. Lacrosse is played with the help of lacrosse sticks with net heads which are used for catching a rubber ball, passing it to each other and shooting the ball into the goal. Netball is similar to basketball. Players throw the ball between three zones of a rectangular court and try to throw it into the hoop of the opponent’s team. CHAPTER 2 ACRONIS ON THE PHONE

At 8.00 in the evening Acronis called her brother Aeneas. “Is that you, little pig?” asked Aeneas. “Yes, it’s me. Listen, I need to decide on a project for this term. These are the options: ‘The life cycle of a giant peacock moth’ in Biology, ‘Nucleic acids synthesis’ in Chemistry, and ‘Electro­­ mechanical cryptographic machines’ in Physics. Which one should I choose?” “Well, let me think. Chemistry isn’t really your favorite subject, and you don’t know Physics at all. Biology is just boring. Quite difficult to pick one.” “Yeah, but I can ask Dad for help,” Acronis said. “Then let’s try to work out what Dad would prefer. He seems quite indifferent to giant peacock moths. Nucleic acids? Why not? They have something in common with food. Dad might like it. Cryptography… That’s what would get him interested! It deals with the history of cryptography, famous spies, ‘the dancing men’…” “Yes,” Acronis agreed. “There is a German cryptographic machine in the our school — ‘Enigma’! It’s been brought from the museum. I think Dad has found it interesting.” “So, there’s nothing to think about — take the Physics project! You may become another Marie Curie one day.” “Don’t be silly. Ok, I’ll speak to Mum about this. By the way, are they really getting divorced?”

11 “One day they are, the next they aren’t,” Aeneas explained. “It’s complicated. They have to divide nineteen variants to decode it and that would take decades. And yet the code was broken. Thanks possessions, their children…” to this, our pilots won the Battle of Britain.” “I wonder how they are going to divide me?” Acronis asked. “Ok, Dad,” Acronis said. “I’ll have some time at the end of this week, and you’ll tell me more “I think Mum will get your head, and Dad is getting your legs,” Aeneas suggested. about the Enigma machine, how it was broken and how to design a cryptographic device which is “Stop it! Anyway, I’ve got to go. Send my greetings to Johnny.” impossible to break.” “I will! Call me tomorrow.” “With pleasure!” Dad was happy. “Call me when you have time.” Acronis dialed her mum’ s number. “I’ll try,” Acronis promised. “Bye for now. Mum said she hadn’t decided yet whether she wanted “Mum, you gave me the wrong sweater for lacrosse,” she said first. to divorce or not.” “Don’t talk nonsense,” Mum said. “Of course I gave you the right one!” “Very nice,” Dad replied. “Sleep well!” “I need a purple sweater with white letters on it, but the one you gave me is beige.” “Good night!” “Turn it inside out!” Acronis ended the conversation, put the phone into her cupboard and took out a box of jelly “Ah… you’re right,” Acronis got a bit embarrassed and immediately moved on to her second babies to treat her roommates. Acronis was sharing a room with Min Qiu from China — the question. “What subject should I choose for instantly my project? Physics, Chemistry or Biology? cleverest pupil in the class, two Nigerian girls, Naomi and Victoria, quiet Abangu from Somalia, “Physics, of course!” Mum replied instantly. “Your Dad isn’t good at Chemistry or Biology. and three English girls: a hockey player, Izzy, a swimmer, Carin, and Shelly, who was the nicest of “Ok,” Acronis said. “Are the two of you really getting divorced?” all: Acronis had made friends with her earlier. “Actually, I haven’t decided yet,” her mum replied. “Any other questions?” “When Miss Parfitt comes in, all of us have to be in bed,” Shelly instructed Acronis. “So, now put “No. Can you transfer some money to my account, about forty pounds, please?” your pyjamas on and get under the blanket. When Miss Parfitt leaves, we can sit in the dark and “Thirty will do. Don’t forget to brush your teeth and put your earplugs in before going to bed.” chat quietly.” “I will, Mum.” “I see,” Acronis said and obediently crawled under the blanket. The day had been long and “Well. Bye. Kiss,” Mum said, and then she hung up. extremely busy. Acronis wanted only to close her eyes for a second, but when Miss Parfitt came in, Acronis called her father. the girl had already fallen fast asleep. “How’re you, Sunshine?” Dad asked. “I’m fine. What are you eating?” Acronis could hear her dad was chewing something. ∑ “You see, I ordered a grilled rib-eye steak. It turned out not only to be terribly overdone, but they also mercilessly coated it with boiled vegetables…” “I got it. Dad, we’re going to do a project on cryptographic machines.” “That’s great!” Dad was delighted. “I’ve seen a perfect sample of ‘Enigma’ in your school.” “So have I,” Acronis said, “what is it?” “Oh!” Dad exclaimed. “The Enigma machine is a masterpiece of engineering! It was considered the most reliable coding device in the world. One would have to run through ten to the power of

12 CHAPTER 3 ADVENTURES ON HYPERBOLA ROAD

The way from Finley house to the academic buildings passed along the green and quiet Hyperbola Road. Every day, from Monday to Saturday, Miss Parfitt took the girls to Hyperbola Road, where they were organized in pairs to set off for classes. On her first day at school, Acronis was paired with Shelly. While walking, Acronis kept looking around, trying to remember everything her new friend was saying about school life. “The most boring classes are Latin and Greek. Mrs. Greenfield, the teacher, is almost deaf, so we can even have some quiet chats in class. And it’s better to sit closer to Miss Fergusson in Maths. She always calls out pupils sitting at the back of the class. Our Biology teacher is Mr. Paul. Last time he brought a rat to the class. Can you imagine? It turned out that Miss Holly was terribly afraid of rats. She popped in the class and started screaming! Have you chosen a musical instrument?” Shelly changed the subject unexpectedly. “Yes, harp,” Acronis answered. “but Dad hasn’t brought my harp from home yet — it’s very heavy.” “I see. Have you got a part in our drama?” “Not yet. What are you staging?” “‘Hamlet’. I can’t believe I’m going to play Laertes! I’ll have to take fencing lessons from Mr. Marshall.” At this moment the girls’ attention was drawn to something unusual. They spotted a strange couple at the corner of Hyperbola Road and the High Street. The man, who had a camera resting on his shoulder, was wearing round headphones. The woman was holding a microphone. When

15 she saw the bunch of girls, she headed towards them, put the microphone in Victoria’s and Naomi’s faces and started speaking. “Through our sources, we’ve learned that two daughters of the Minister of Oil, who was arrested in Abuja yesterday, are studying in one of the best schools in England. What do you think about the accusations made against your father, girls?” Miss Parfitt flung herself in front of the woman blocking her access to the girls. “Our pupils do not give interviews! If you have any questions, send an official request to the school!” she said furiously. Shelly grabbed Naomi and Victoria and together they ran towards the doors of the Department of Ancient Languages located nearby. Acronis followed them. The argument between the woman with a microphone and Miss Parfitt was going on. “Can you confirm that the girls’ studies in England are paid for by the corrupt Minister Murtalu?” “I will not make any statements. Go away before I call a policeman!” Shelly touched a sensor at the school’s door with her finger. The lock flipped, and the girls rushed inside. In the spacious lobby of the Department of Ancient Languages they were met by a tall, elderly lady wearing glasses and a smart suit. This was Mrs. Greenfield. “Go to class, don’t be late!” she hurried them up. Acronis noticed that Naomi was sobbing and Victoria was wiping her eyes with a paper tissue. When all the girls occupied their desks in Latin class, Mrs. Greenfield started doing a headcount: “Shelly Windfall.” “Here,” answered Shelly. “Carin Dawning.” “He re .” “Victoria Johnson.” “He re .” “Naomi Johnson.” “Here,” wept Naomi. “The only thing I can’t understand is how they can be the daughters of Minister Murtalu if they are Johnsons,” whispered Acronis to Shelly. Shelly said nothing. ∆ 16 CHAPTER 4 CHATTING UNDER THE BED

Life in the boarding school was full of contrasts. On the one hand, pupils were taught how to be disciplined and punctual — their days were strictly planned and structured. On the other hand, girls were absolutely free in the evenings, provided that they did not leave the school territory. Once Acronis realized this simple truth, she took up a habit of spending half an hour under her bed before sleep. Nobody could see her there, and hardly anyone could hear her. Lying under her bed, Acronis would phone her parents, brother, or her friends from the previous school. Once she even called the famous racer John Macintosh, who was her brother Aeneas’ best friend. “Today, some journalists followed two of my classmates in the street,” Acronis said quietly to Aeneas on her first evening. “It is supposed they are the daughters of Minister Murtalu arrested in Nigeria. Actually, their surname is Johnson.” “They might have another name,” Aeneas suggested. “But how did the press discover that?” “I know how they did!” Acronis exclaimed. “Somebody hacked into the school’s computer. I’ve heard our Physics teacher Miss Holly telling Mr. Paul about that. The lists of pupils must have been leaked to a social network.” “That’s bad for the school’s reputation,” Aeneas said. “They should keep their secrets better.” “Speaking about secrets, by the way,” Acronis continued. “Do you know who invented the book cipher?” “Haven’t got a clue…”

19 “Aeneas Tacticus! He was an ancient Greek military general. Miss Holly told me about him today. Maybe you were named after him?” “I don’t think so,” Aeneas said. “When I was a child, Dad read the poem ‘The Aeneid’ thirty times in a row to me. I recon, when choosing my name, our parents meant the Aeneas from Troy, not the Tacticus one.” The book cipher “Well, Aeneas Tacticus popularized the book cipher. Although, it was more convenient for Is a cipher in which two figures are military people to use the Caesar cipher. Caesar just shifted one alphabet relatively to another. assigned to each letter. The first figure is a number of a line on the relevant page Every letter of one alphabet corresponded to a letter in another one. The number of positions the of a code book, the second figure correlates alphabet was rotated on was the key of that cipher.” with the number of order of letters ICTIONARY

“That’s quite a simple code,” Aeneas said. in a line. Only the person who possesses D “Yes, exactly. This code was used by the Germans in their Enigma machines!” Acronis was the code book and the key with the page showing off her erudition. “Only that Enigma machine changed the cipher after each letter.” number is able to read the message. “Really? After each one? How could they manage that?” “I haven’t quite got it so far,” Acronis confessed. “Miss Holly told me that every click of an Enigma key caused the movement of disks, which changed the electric circuit connecting the letters of two alphabets. Something like that… You know what?” Acronis exclaimed suddenly. “Tonight, when Miss Parfitt is fast asleep, I’ll try to switch on our Enigma machine and have a look at how it works.” “And you’ll be immediately expelled from school!” Aeneas predicted. “No way! I’ll say that I’m a sleepwalker. So, I came up to the Enigma machine without even noticing it myself. I hope you and Dad will confirm that if needed!” The Caesar cipher Is a kind of a shift cipher used by ∏ the Roman emperor Gaius Julius Caesar when corresponding with commanders of his legions. Every letter of the Roman alphabet stood for a letter shifted relatively to the first one on a certain number of positions. For example, instead of “A” Caesar wrote “D”, instead of “B” – ​“E”, “C” was turned into “F”, etc. CHAPTER 5 THE MYSTERY OF “ENIGMA”

Miss Parfitt walked in the room. She was carrying a basket where the girls had to put their mobiles. This happened every evening when free time was coming to an end and the girls were going to bed. “Now rest!” Miss Parfitt said. “You’re rehearsing ‘Hamlet’ tomorrow. Have you got your part, Acronis?” “Yes, I have,” Acronis answered. “I’ll be playing Rosencrantz.” “That’s great. You’ll need a black jacket and a white-­collar shirt.” “Yes, I know. I’ve told Mum.” “You can rehearse with Abangu. She is playing Guildenstern. You will be together all the time on the stage. Am I right, Abangu?” The girl nodded silently. “Perfect! Good night, girls!” said Miss Parfitt and left the room. “Have you got a black jacket and white collar?” Acronis asked Abangu. “No, I haven’t,” Abangu answered. “Do you want me to ask my mum to send two costumes for us — one for you and one for me?” “No, thanks,” Abangu said and turned away from Acronis. Acronis thought it was much more difficult to make friends with her classmates than she had expected, though it was not worrying her that much for the moment. That night Acronis decided to switch the Enigma machine on and, for starters, code her name. Let the one who can decode it find out that it had been her!

23 Acronis tossed and turned in her bed until midnight, and then she finally thought that Miss Parfitt must have fallen fast asleep. The girl quietly got out from under the blankets and sneaked to the door. Trying to open the door carefully so that its rusty hinges would not make any noise, she went out of the room and into the corridor. The metal keys of the Enigma machine were gleaming at the end of the corridor. Acronis tiptoed to the case with the cryptographic device and tried to move the glass lid away. Just when she had almost managed to do it, the lights downstairs switched on. “Is miss Parfitt still awake?” Acronis gasped to herself, and then she squatted down next to the Enigma machine case, pretending to be invisible. Acronis could hear the entrance door squeaking. “Wait here, the girls will come downstairs soon,” she overheard Miss Parfitt’s voice. To Acronis’ surprise, in a second the door of her own room opened, and two dark figures appeared and moved along the corridor towards the stairs. When they reached her, Acronis recognized Naomi and Victoria — both of them were carrying heavy bags. “Where are you going?” whispered Acronis. “We are being sent to another school!” Naomi whispered back. “Say our goodbyes to the girls, will you?” “I will…” Acronis looked puzzled. “But why?” Naomi and Victoria were already on the ground floor. “Goodbye, Miss Parfitt! Thank you, Miss Parfitt!” could be heard from there. Somebody sniffed. Then, the entrance door shut, the lights switched off, and Finley house plunged into silence, as though nothing had happened. Acronis touched the glass lid of the case again and moved it by several inches. Then she put her hand in and pushed the key “A”. The light “V” immediately came on, and three disks fixed in the middle part of the machine started to spin. In the silence of the sleeping building the ticking they were making sounded like a bell toll. It stopped in a second, the disks became still, and the light went off. At that very moment the door downstairs creaked, and Miss Parfitt’s steps could be heard. Calmly Acronis put the glass back on the case and tiptoed to her bedroom — just in time not to be caught. λ 24 CHAPTER 6 ENCRYPTIONS AND CODES

Dad came on Sunday. He brought the harp which was so big that even with its legs off it could hardly fit the Land Rover’s boot. Acronis showed Dad the way to the music school. Together, they drew the heavy instrument into a dark hall with three other similar harps standing in a row. At this point, the official purpose of Dad’s visit was fulfilled, and they could have lunch — Acronis still had two hours of free time left. “Shall we go to McDonald’s?” the girl asked hopefully. But when it came to food-related issues, Dad was rather firm. “Next time, if you want, we can go to a Japanese restaurant. Today I booked a table at ‘Henry and Joséphine’ — it’s a good place, they have two Michelin stars.” “Oh, it’s going to take too long. I’ve got only two hours…” Acronis groaned. “I’ve thought it over, Sunshine!” Dad objected. “We’re going to skip dessert! So we’ll fit in two hours. If not, we can tell Miss Parfitt that our car broke down and we had to take a taxi.” “Let’s have dessert but skip the rest instead,” Acronis suggested. “Well, if you insist…” Dad did not seem very happy. “Then you get dessert and I’ll have a cheese plate.” “Great!” Acronis was glad. “And you’ll have to explain me how to decrypt the Enigma cipher.” Dad was delighted with an opportunity to give Acronis a detailed lesson on cryptography.

27 “You probably know, Sunshine,” Dad started as soon as a waiter had taken their order, “that there are twenty-six letters in the Latin alphabet; the Enigma cipher encodes each letter by another letter of the alphabet.” “Wait, wait!” Acronis interrupted. “Every letter of the alphabet stands for another letter of Alan Turing the same alphabet, but the second one is shifted on several positions relative to the first one. Is an Officer of the Order Am I right?” of the British Empire, a Fellow “Not really,” Dad muttered. “It is true that each of the twenty-six letters corresponds with of the Royal Society, an outstanding another one, but what goes with what is defined by the position of the three rotating disks of the English mathematician, the founder of Informatics and Enigma machine.” the author of the first computing ICTIONARY

“Aha! So, it’s not the Caesar cipher then! Miss Holly’s cheated me!” algorithm. During the Second D “No, she hasn’t.” Dad stood up for her teacher. “The Caesar cipher is a particular case of the World War, Turing led a group Enigma cipher.” of British scientists at Bletchley “Ok! Go on, please!” Park, who created the “Turing Bombe” — a computer which “The infernal ruse of the Enigma is that its disks turn after each press of a key, which causes a decrypted the Enigma cipher. change of the code. It is governed by the configuration of an electric circuit passing through a letter key, three disks, the switchboard panel, the reflector and one of the lights. Each rotation of the disks leads to disconnection of old circuits and connection of new ones. The number of possible combinations of disks is much bigger than the number of letters in the encrypted message. So, every single letter has its own unique code.” Michelin “Last night I encrypted the letter ‘A’,” Acronis boasted. “At the top panel of the Enigma machine Is a French industrial the ‘V’ light was on.” corporation, publishing a world- “That’s great!” Dad praised Acronis. “Have you tried to press the ‘A’ one more time?” famous restaurant reference “No,” Acronis looked abashed. “Miss Parfitt left her den and I had to run away.” book. The best restaurants in the world are awarded “If you’d managed to do it, you’d have noticed another light come on,” Dad explained. from one up to three “stars” “I see! But if one letter in the original word matches so many letters in the encrypted one, how is in this book, depending it possible to decipher a received message? How did the Germans manage to read their messages?” on the rating of a restaurant. Acronis wondered. “With the help of the Enigma machine.” Dad smiled. “The machine could encrypt and decrypt messages. To read an encrypted message, the operator took a daily code from the codebook. It included all settings of the switchboard, options and the start position of the disks. Setting the Enigma machine into the position prescribed by the codebook, the operator retyped an encrypted

28 message by pushing the keys of the machine. Each push of a key caused the light with a letter on. These letters made a decrypted text.” “I got it!” Acronis exclaimed. She finished her dessert while Dad was speaking. “It’s not so difficult.” “No, it isn’t,” Dad agreed, “though it looks so. To decrypt a captured message the British Intelligence Service had to have the same Enigma machine with the same set of disks. What’s more, it was necessary to know the start position of all disks and switches used by the German cryptographer.” “So, how did they manage to do that?” Acronis started consuming some cheese from her dad’s plate. The man was so absorbed in his explanation that he did not even notice it. “It wasn’t a big deal to get an Enigma device. Some examples had fallen into the hands of allied intelligence services even before the war started. The problem was in learning quickly how to guess all the initial settings of the Enigma machine as they were different for each new encrypted message.” “But they could also steal the codebook,” Acronis suggested. “Usually there were just two copies of such books. The operator of the transmitting machine had one, and the operator of the receiving device had the other. Besides, two German operators often agreed how to shift the position of disks before the beginning of a communication session in order to mislead the British completely.” “Well, they could try different settings.” Acronis took the last piece of cheese from the plate. “By rotating disks, flipping switches on the switchboard, sooner or later, you could guess the start position and read the text.” “Unfortunately, Sunshine,” Dad objected, “there were billions and billions of options. Checking them all for a short period of time, typing an encrypted text for each position and making sure the description is worth something. That was an impossible task for an army of cryptographers.” “Don’t you think a computer could easily do that?” Acronis asked. “Yes, it could!” Dad exclaimed. “You’re absolutely right! The only problem was that there weren’t any computers in the world. They just didn’t exist. That is why they had to be invented. And it was done by…” “Alan Turing!” Acronis rattled off, not letting her dad pause for effect. “It’s clear now! Miss Holly told me about him. The question is how he did it. You’ll tell me about that next time, Dad. We’ve got to go now, otherwise I’m going to be late for the rehearsal.” Dad gave a sad look at his empty plate and asked for the bill. β 30 CHAPTER 7 THE DUEL

Rehearsals of “Hamlet” were taking place in an old-fashioned school theatre, with a run-down stage and a scruffy velvet curtain. The small part of Rosenkrantz, which Acronis had been given, was not very interesting. Shelly was much luckier. When playing Laertes, she had to duel with Hamlet himself — a beautiful French girl, Marie-Rose, from the other class. Both girls were running on the stage poking their cardboard swords at each other until Miss Sikorsky, the Drama teacher, made them stand in a graceful position. Marie-Rose caught her breath and declared in a dead voice: “Come, for the third, Laertes: you but dally; I pray you, pass with your best violence; I am afeard you make a wanton of me.” Shelly answered back: “Say you so? Come on.” And they started fighting again. When Shelly was performing another leap, a small piece of paper fell out of her pocket. It flew through the air and fell on the floor next to Acronis. Acronis picked up the scrap of paper, intending to hand it back to Shelly after the duel. Looking at her find, Acronis saw a row of numbers: 618 233 700 464. Paying little attention to this combination, Acronis put the paper into her pocket, and soon she forgot about it.

33 “Have at you now!” yelled Shelly and stabbed Marie-Rose with her cardboard sword. Marie-Rose “Can I have a look at the list of pupils again, please?” the Chief Inspector interrupted her. fell down quite awkwardly. “Of course, you can! Let me show you the way to my office.” Mrs. Jellicoe, followed by the Chief “Swap your swords!” advised Miss Sikorsky. Inspector, headed to one of the doors. In a second, the little courtyard was empty. Abangu closed Marie-Rose sprung to her feet and jumped towards Shelly. The swords fell down on the floor, and the window and stared at Acronis intently. the girls simultaneously bent over to pick them up. When collecting the swords, they could hardly avoid “What were they talking about?” Acronis looked embarrassed. “A theft?” bumping into each other. Finally, Shelly got Marie-Rose’s sword, and Marie-Rose got Shelly’s one. “My dad’s letters were stolen,” Abangu said calmly. “Good one,” praised them Miss Sikorsky. “Done!” “Letters? Stolen? When?” Acronis felt someone touch her elbow. She turned back and saw quiet Abangu in the costume “This morning.” of Guildenstern. “Who would need them? Was there something important in them?” “Do you want me to show you something?” Abangu asked. Abangu did not answer. She looked at Acronis in silence. Acronis felt very uncomfortable. “Yes, I do…” Acronis agreed. She was quite perplexed trying to figure out what it could be. “You don’t think it is me who’s stolen them?” Acronis asked resentfully. “Why would I need them?” Abangu and Acronis walked out of the theatre. Nobody would notice their absence: Miss For a while Abangu remained silent, but then she said: Sikorsky was busy explaining to the girls the scene with the poisoned cup. “Yesterday you were talking about a book cipher. I could hear you when you were lying under Abangu took Acronis to a little window in the corridor, which led from the theatre into the your bed.” library. Looking out of the window, Acronis saw a tiny cobbled courtyard with four doors leading “Yes, I spoke about it to my brother. His name is the same as the name of the book cipher’s into it. There was a bronze bust on a cylindrical pedestal in the middle of the courtyard. A stranger inventor.” Acronis was trying to justify herself. was standing next to the bust. He was talking to their strict Headmistress Mrs. Jellicoe. It was “And then you were spying on Naomi and Victoria — at night when they were leaving.” impossible to understand what they were speaking about. “I didn’t spy on them, I swear! I wanted to switch on the cryptographic machine in the corridor. Acronis looked at Abangu with surprise. Abangu put her finger to her lips and tilted the window. We’re not allowed to touch it, I was just curious…” The voices could be heard better. “Swear on your mum, that you didn’t take the letters,” Abangu demanded. “So, Chief Inspector, our teachers are beyond suspicion,” the Headmistress was saying. “I swear on my mum, my dad, and my brother!” Acronis cried. “We will check their alibi once again,” the Chief Inspector answered. “But it may mean that the Abangu seemed satisfied. theft was committed by one of the pupils.” “There was one letter which was encrypted using a book cipher,” she said. “Or one of their parents who visited the school this morning. It could also have been a stranger “Don’t worry!” Acronis consoled her. “Decrypting the book cipher is possible only with the who had managed to get into the school unnoticed. The pool of suspects is too wide.” code book.” “We’ll try to narrow it. We’re going to study the security video footage. Until we have done this, “I know it.” Abangu nodded sadly. in view of the circumstances, there will be a constable on duty in the school.” “Has the book disappeared too?” Acronis gasped. “Thank you very much, Chief Inspector,” Mrs. Jellicoe said. “No, it hasn’t. Let’s go back. They must be looking for us.” Abangu broke off the conversation. “I kindly ask you to keep secret the information about this incident,” the Chief Inspector advised. She quickly walked to the door leading to the theatre, opened it and went in without giving a single “Agreed,” nodded the Headmistress. “We have already become the center of unnecessary attention look at Acronis. thanks to the story of those Nigerian girls. And now this. Who could’ve imagined…” ≈ 34 CHAPTER 8 THE LIQUID LIGHT

Monday started with a Physics lesson. Acronis and Shelly were sitting at the desk in the first row. They barely spoke to each other. Miss Holly was the youngest teacher in their school. Although she was afraid of rats, the girls liked her. This time, Miss Holly was telling them about the light. “Do you know what the light is composed of?” she started. Min Qiu raised her hand. The light is composed of photons, Miss Holly,” she answered. “Well done, Min Qiu! What is a photon?” Miss Holly asked. Min Qiu raised her hand again. “A photon is a very small particle that travels at the speed of light.” “Perfect!” Miss Holly said with admiration. “Perhaps, you can also explain the difference between red and green photons?” Min Qiu hesitated for a second. Acronis decided not to miss a chance and raised her hand. “Yes, Acronis?” asked her Miss Holly. “They differ in colour!” Acronis blurted out. “Well,” Miss Holly nodded. “That’s essentially true. We only need to understand what ‘colour’ means. For a start, let’s remember that colour is one of three properties of a photon. The other two include phase and polarisation.”

37 Acronis noticed clever Min Qiu writing down in her copybook: “Properties of photon. Colour, Phase, Polarisation.” “Let’s look at the screen now,” suggested Miss Holly. She turned on the projector and switched off the lights. The sea surface appeared on the screen. There were parallel stripes of waves running across a greenish and bluish background. The girls started sighing and murmuring — everybody wanted to be at the seaside. However, Miss Holly did not let them dream for long. She paused the video, and with the help of a pointer indicated a crest of one of the waves. “Look at the distance between crests of two neighboring waves. It’s called a wavelength. Now just imagine that the sea is the light. Each colour is characterised by a wavelength. For example, ICTIONARY

wavelengths of the colour blue are much shorter than wavelengths of the colour red.” D Min Qiu drew several waves in her copybook, with an arrow marking the distance between neighbouring waves and wrote down: “wavelength = colour”. Acronis was very envious of the accurate notes made by Min Qiu. Her own copybook was almost empty, if you didn’t mention a little kitten, drawn at the page corner. Acronis’ neighbor Shelly drew with a flourish two quite curvy waves and wrote down next to them: “red colour” and “blue colour” Meanwhile, Miss Holly continued her speech. “Phase is determined by what part of the wave is located in a certain point of space: wave front, crest or the dip between waves. When two waves with the same phase meet, they amplify each other.” Two waves facing each other in the swimming pool of an aqua park appeared on the screen. Indeed, at the point where they met water rocketed up very high forming something similar to a tsunami. The girls remembered time spent in aqua parks and started fidgeting again. “Any wave is a result of an oscillatory motion.” Miss Holly did not let them relax and went on. Photon “For example, particles of water on the wave’s surface always move here and there, to and fro. This is called oscillation.” Is the most widespread particle in the Universe. It has neither mass or electric charge, nor any structure or size. Miss Holly’s speculations about inflatable balloons filled with Now, a float dancing on a lake’ s surface could be seen on the screen. water can not be considered to be an accurate description of a photon. However, Miss “Wave polarisation is determined by the direction of these oscillations,” Miss Holly pointed at Holly is right that photons combine properties of waves (wavelength, polarization, the screen. “The float is moving vertically.” “So,” Miss Holly summed up, “we’ve become acquainted phase) and particles (angular momentum, momentum, energy). with three properties of light: wavelength, phase and polarisation.”

38 Acronis raised her hand. “Now, write down your homework,” Miss Holly commanded. “Each of you has to make a “I’m sorry, I haven’t quite got it. How is it all connected with light? At the beginning you said rainbow. You will make a rainbow from the sunlight by projecting it onto the white screen in that light consisted of particles, photons. Then you said that photons had three properties. Now it our class. For that purpose you will borrow some prisms from our laboratory and try to split the looks like these are the properties of sea waves rather than photons!” sunlight into different colours. Girls gazed at Acronis with admiration — she asked such a difficult question. Min Qiu wrote down: “Question: What does a photon and a wave have in common?” Ξ “Well done, Acronis!” praised her Miss Holly. “I’m a silly goose, I forgot to give you the most important information.” Actually, Miss Holly did not look like a goose, and definitely not like a silly one. The girls started giggling. “The thing is that our photons are special particles. They are not like tennis balls. Every photon has much more in common with the wavy sea surface. That is why the state of a photon is determined by the three parameters of a wave. Is that clear?” “Not really,” Acronis confessed. “What is happening when the light goes, for example, from the Sun to the Earth? Is it that particles are flying, the waves are running or the whole piece of sea is moving?” Miss Holly took her time to think it over. Finally, she said: “Albert Einstein, who combined wave and particle theories of light, would answer this question better than me. However, I’ll try to explain. The sun constantly emits light, billions and billions of photons every second. All these photons are moving from the sun at the same speed; thus, they form something like an ocean with enormous number of waves of different wavelengths, phases and polarizations. If we didn’t have the sun, but the source of single photons — these days such sources can be made in a physics laboratory — that source would generate ‘pieces of sea’, so-called wave packets. If you look at it from a distance, it’s like an inflatable balloon. If you catch a balloon-photon with a photodetector, you will be able to measure its wavelength, phase and polarization with a certain degree of accuracy.” Girls were sitting slack-jawed. Min Qiu neatly drew the sun in the middle of the ocean and a balloon with some water inside. Her notes read as follows: “multiphoton source of light” and “single photon”.

40 CHAPTER 9 OVER A GLASS OF PIMM’S

On Wednesday, Acronis’ school was playing lacrosse against the Winchester Boarding School for Girls. Mum came to see the match taking place on a green pitch, which had recently been sold to the school by a local farmer. Mum got a glass of Pimm’s from Miss Parfitt and stood under the shed. Parents of the girls from the “B” team, where Acronis played as an attacker, had been already gathering there. Eight girls from Winchester were wearing sandy yellow sweaters. The nets on their sticks were also yellow. It was a strong team: in the first minute of the match the forward of Winchester School threw the ball across the middle of the pitch. It flew above the goalkeeper’s shoulder and into the goal of Acronis’ team. Mum was not really interested in lacrosse, but she did not mind talking to the parents of Acronis’ classmates. Shelly’s father, who was standing nearby, had the most civilized look. “Not the best weather for the match today, is it?” Shelly’s father said, politely starting some small talk, when Acronis’ mum waved at him. “Terrible!” Mum confirmed indifferently. “According to the forecast, it will be raining until the end of the week.” At that moment, Acronis scored a goal. Parents started cheering her. “Your daughter is quite noticeable on the pitch,” Shelly’s father said, meaning Acronis’ reddish plaits. “As is Shelly!” Mum said hinting at the curly hair and fairly plump figure of Shelly playing in defense.

43 At that moment a stranger wearing a grey suit and a tie addressed Mum. “Chief Inspector Loring,” he introduced himself. “Could I have a word with you in private?” Mum had to excuse herself and stepped aside with the Chief Inspector. “Of course, you’ve heard about the recent unpleasant events,” he started. “Do you mean the Nigerian girls and the story about the letters?” Mum asked. “Yes, I read Mrs. Jellicoe’s messages.” “Very good. That means I don’t have to share the details of the case that I’ve been asked to investigate. I’ll get right to the point. Yesterday your daughter took her black jeans to the laundry.” “Yes, they got dirty when she was heating up a chocolate pudding in the microwave,” Mum said. “The laundry staff are obliged to shake the clothes that are about to go to the laundry and check the pockets. Many pupils leave their chewing gum, brushes, and even mobile phones,” the Chief Inspector continued. “This is what was found in the pocket of your daughter’s jeans.” He opened his briefcase, took a transparent plastic bag out of it and showed Mum a little scrap of paper covered with numbers. “So what?” Mum asked. “You see, this is a part of one of the stolen letters,” the Chief Inspector said bleakly. “A very important part: this is the cipher key used by its author. Obviously, an offender destroyed or hid the letter but kept the key to use it one more time.” “Do you think my daughter is such an idiot that she has taken her jeans, with the cipher in the pocket to the laundry after all those clever tricks?” Mum wondered. “I just wanted to ask you, Madam, if Acronis gave you any information which could help our investigation,” the Chief Inspector seemed a bit embarrassed. “No, she did not. Why don’t you ask her?” “I’m about to do it! Could you sign a consent, please?” The Inspector took out a sheet of paper with the text: “I allow Chief Inspector Loring to ask my daughter several questions related to the police investigation.” Mum signed the paper, said goodbye to the Chief Inspector and went back under the shed. “You’ve missed the most interesting part!” Shelly’s father met her there. “Acronis has scored three more goals. We are winning 6–3!” Ω 44 CHAPTER 10 A MUSIC LESSON

Harp lessons always seemed a waste of time to Acronis. There was nothing more boring than endlessly sitting next to a huge, awkward instrument with the strings which couldn’t produce any sounds pleasant for a human ear no matter how well you plucked at them. Four harp players gathered at the lesson of Mrs. Brauhich: Izzy, Carin, Marie-Rose and Acronis. Marie-Rose was the only good one in the quartet. Last term she had even passed the level 3 diploma with honours at the exam. While one girl was playing, the others had to listen silently. The music teacher, Mrs. Brauhich, reacted quite resentfully even to the sound of a squeaking chair. Fortunately, in the middle of the lesson Mrs. Brauhich was called to the phone, and the girls were left alone. Izzy and Carin started discussing their forthcoming holidays. Parents were going to take both of them to Greece to get started in sailing. Marie-Rose told everybody she would visit her grandmother in Limousin. Answering the question about holidays, Acronis said: “If my parents haven’t divorced by then, we’ll go to the motor racing in Dubai, then Italy, then…” At that moment Mrs. Brauhich came back. “Acronis, go to Mrs. Jellicoe, please, she wants to see you,” instructed Mrs. Brauhich. Acronis happily stood up. “You will come back and finish the exercise after classes!” The words of Mrs. Brauhich followed Acronis. Having nodded carelessly, Acronis left the class, ran through an empty hall with marble columns, and knocked on the oak door of the Headmistress’s office.

47 “Come in!” Mrs. Jellicoe thundered. Shelly, puffed out and disheveled, came into the room. She was wearing a tricot for fencing. The Acronis entered the office. The Headmistress was sitting in a chair behind her writing desk with scene with the Inspector’s introduction and the demonstration of the piece of paper was repeated. a bronze inkstand and an old-fashioned telephone on it. In front of her, in one of the armchairs Shelly looked at the numbers, seen through the plastic bag, and finally said: for guests, the Chief Inspector, whom Acronis had seen the day before, was sitting. “No, I don’t remember seeing this note before.” “Let me introduce you to Chief Inspector Loring,” the Headmistress said. “He is going to ask Acronis wanted to contradict, but the Chief Inspector gave her a sign to keep quiet. you some questions.” “Tell me, please,” he asked Shelly, “who took part in the rehearsal of ‘Hamlet’ on Sunday?” “Good afternoon, Chief Inspector!” Acronis started. After a boring music class this meeting “Almost everybody did!” Shelly was trying to remember. “Marie-Rose — Hamlet, me — Laertes, was a real gift for her. Izzy — the Queen, Carin — Claudius, Min Qiu — Horatius, Acronis — Rosencrantz, “Hello, Acronis,” the Chief Inspector responded. He was looking at Acronis attentively. “Tell Abangu — Guildenstern… We didn’t have Ophelia or Polonius — Naomi and Victoria were going me, please, if you recognize this piece of paper?” to play them. The Gravedigger and the Ghost of Hamlet’s Father were played by Miss Sikorsky He showed Acronis a plastic bag, like the one which is used for keeping stamps. There was a herself. scrap of paper with numbers 618 233 700 464 written on it. “If I understand correctly, between rehearsals your costumes are stored in the wardrobe of Miss “Of course, I do!” Acronis exclaimed. “I picked up this note the day before yesterday, when Sikorsky?” the Chief Inspector asked. we were rehearsing ‘Hamlet’. Then it disappeared; probably, I left it in the pocket of the trousers “Yes, that’s right,” Shelly confirmed. I took to the laundry.” “Tell me, please, when you were putting on the costume of Laertes, did you check your pockets?” The Chief Inspector nodded. “Pockets? But there aren’t any pockets in the Laertes costume!” Shelly looked surprised. The “So, you can confirm that you found this scrap of paper in the school theatre? When was it?” Chief Inspector and Mrs. Jellicoe looked at Acronis. “On Sunday. We were having a rehearsal. The piece came out of Shelly’s pocket and flew away. “That’s right.” Acronis tried to justify herself hastily. “We all play in black jeans. I mean the girls I caught it and put it in my pocket because I was interested in the numbers written on it.” playing male parts. On the top we put on white shirts and jackets. This piece of paper was in the “Shelly Windfall? Are you sure?” the Chief Inspector asked. pocket of Shelly’s jeans.” “Of course, I am!” Acronis exclaimed. “No, it wasn’t,” Shelly stated. “At least, I didn’t put any scraps of paper in the pocket of my jeans. “We will have to invite Shelly here and ask her to confirm your words,” the Chief Inspector Except for some paper napkins.” concluded. “Thank you!” the Chief Inspector said. “Both of you can go back to your lessons.” “Shelly is at her fencing lesson now,” the Headmistress joined their conversation. “I’ll ask Mr. After leaving the room Shelly asked Acronis: Marshall to send her here. Acronis, wait over there.” She pointed at a sofa in the corner of the “Do you know anything about that strange piece of paper?” room, dialed a number using her old telephone and thundered: “I think,” Acronis said, “the set of numbers on it is the key to a cipher. Each of four numbers “Mr. Marshall? Could you ask Shelly Windfall to come to my office?” corresponds to the number of a page of some very thick book Abangu is reading.” Acronis sat on the sofa, ready to wait. In a minute, she heard somebody walking fast in the “A thick book?” Shelly wandered. “The only thick book I’ve seen Abangu with is a volume of corridor. Then there was a knock at the door. Shakespeare!” “Come in!” answered Mrs. Jellicoe. Φ 48 CHAPTER 11 THE TURING BOMBE

That very evening Acronis hid in the bathroom to call Aeneas. “This is not a school but a den of thieves!” Aeneas was impressed after he heard the story about the letters, the cipher and the Chief Inspector. “Do you think Shelly really doesn’t know where that scrap of paper came from? Maybe somebody slipped it into her pocket?” “You can play a trick on the girls,” Aeneas suggested. “Tell them that you know who stole the letters, and that you’re going to inform the Сhief Inspector about it. The criminal will definitely react to it and try to kill you. So, you will know who it is!” “No, thanks,” Acronis contradicted. “Leave that kind of trick for yourself. I’ve got a better idea!” She said goodbye to Aeneas and called Dad. “How are you, Sunshine?” Dad asked. “Very well! So, how did they manage to decrypt the Enigma machine’s cipher? “To cut a long story short without going into details…” Dad began from afar. “Yes, please — keep in mind that in five minutes I have to call Mum, and then Miss Parfitt will come and take my phone away!” Acronis hurried him up. “Ok, ok!” Dad hastened to continue. “Well, the Turing machine was going through different variants. The machine consisted of twenty-six Enigma machines joined together. Their disks were spinning until the machine found the configuration, which had been used by the German

51 cryptographer. When moving, the disks would make a ticking noise. That is why the device was called Turing Bombe — it sounded like a ticking time bomb.” “Wait, wait,” Acronis objected, “you said it was impossible to go through all the options. There were too many!” “That’s right!” Dad confirmed. “But Turing noticed that many messages started with the same words. For instance, every morning, the Centre of Meteorological Observations Luftwaffe sent to aerodromes a weather forecast for the day. All those messages began with the phrase ‘weather forecast’ in German. At least, this was the suggestion of English specialists in decryption. And they proved to be right! The Turing Bombe’s task was to decode two initial words of each message and ICTIONARY

compare the result with the text: ‘weather forecast’ As soon as the machine registered a coincidence, D it was known at Bletchley Park: that day’s key was found — it was possible to start decryption of all Luftwaffe’s messages.” “So easy?” Acronis wondered. “Was it enough to learn two words to crack it?” “Not entirely!” Dad answered. “The problem was that even for getting those two words the Turing Bombe had to spin too long. Alan Turing noticed one more important feature of the Enigma cipher: the German machine assigned a letter to each of the twenty-six letters of the alphabet, but it was impossible to encrypt a letter with the same letter.” “Ah! You mean that ‘A’ could be encrypted by ‘B’, ‘C’, ‘D’ and so on, but never by the letter ‘A’.” Bombe and Colossus “Exactly!” Dad exclaimed. “Thus, the number of variants which had to be tried was significantly Were the first computers designed by Alan Turing and his colleagues from Bletchley reduced. Let’s count how many ‘E’s there are in the phrase ‘weather forecast’! Turing knew for sure Park. Bombe’s algorithm represented a conditional loop: the machine tried different that every time this letter would be substituted with another one in an encrypted message. After variants of the code until the result coincided with a given piece of text. Colossus was looking at a German ciphered message, he could easily find such letters and give an appropriate an electronic machine based on vacuum lams. 1500 lamps ensured a speed of 500 task to his ‘Bombe’ to select start positions of the disks which could transform, for example, the first operations a second. Both a captured encrypted message and a decrypted piece (usually the first words or a signature) were entered into Colossus. The computer ‘E’ into ‘X’, the second into ‘P’, and the third one into ‘W’.” selected the key to the text fragment. Using that key, it predicted the German “Ok, Dad, I think I’ve got it!” Acronis interrupted. “Now I’ve got to call Mum.” She dialed her encryption machine settings, which allowed the rest of the message to be decrypted. mum’s number. “Hello!” Mum said at the other end of the line. “Mum, can you tell me what you know about Shelly Windfall’s parents?” Acronis asked. “Nothing special,” Mum answered, “just normal parents. As far as I know, Shelly’s father is in a board of one of the banks in City, and her mother is a psychologist.” “Ok, what about Abangu’s dad?”

52 “I think he’s the ambassador of Somalia, some kind of diplomat at least.” “Are there any reasons for Shelly’s parents to spy on Abangu’s father?” “I doubt it!” Mum chuckled. “I see! There’s something else. Could you put like, seventy pounds on my account, please?” “Fifty will be enough!” Mum cut her off. Having finished her phone calls, Acronis went back to her room. Some girls were sitting on their beds with mobiles and Kindles. Abangu had a thick volume of Shakespeare on her knees. Shelly was lying on her stomach waving her legs and singing. “I know who stole the letters and hacked the school’s computer,” Acronis announced. “I’m going to talk to the Chief Inspector tomorrow!” After saying that, she lay on her bed and closed her eyes. Miss Parfitt came into the room. She collected mobiles from the girls and wished them good night. “Don’t forget you’re having a Math’s test tomorrow,” Miss Parfitt reminded them. “Try to get a good sleep!” Θ

54 CHAPTER 12 THE TRAP

As soon as the lights in the room went off, the girls surrounded Acronis’ bed. “How come you know this? How did you guess? When?” They kept asking. Acronis answered everybody at once. She sounded calm but firm. “I’ll tell you, girls, but only after I’ve talked to Chief Inspector Loring. Before that I have to keep silent, I hope you understand the rules.” Saying this, Acronis put on her pyjamas, the ones with white sheep on them, and disappeared under the blankets. Girls went on chatting for twenty minutes more, but Acronis did not take part in their conversation, pretending to be asleep. In fact, she was thinking hard. When talking to Aeneas she had acted like she did not agree with his humorous suggestion to provoke the criminal into action by announcing she knew their name. It was a trick. Actually, Acronis came up with the idea to draw the fire upon herself before the conversation with her brother. She just did not want to scare him and disclose her secrets beforehand. Now, lying in the dark, waiting for a sudden attack, Acronis was remembering everything she knew about the girls and weighing up the chances of each of them being the mysterious thief or burglar. “Well… Shelly,” Acronis started thinking, “the sweetest, loveliest and friendliest girl in my school. She likes singing, jumping, fencing and acting in the theatre. Her mum and dad live in England. These are facts standing for her. There is just one thing against her — the piece of paper with the cipher key fell out of her pocket. On the other hand, that piece of paper could have been planted

57 on her without her knowledge. Why would she need to steal lists of pupils hidden somewhere in “I could lie here pointlessly for a long time!” she thought finally. “Obviously, nobody is going to the school computer? Why would she need the letters of an African diplomat, Abangu’s father? attack me while I’m staying in my bed surrounded by five girls. What if I go to the corridor? the No answer.” criminal will follow me. I’ll catch them there.” “Now, Abangu,” Acronis switched to another suspect, “a strange shy girl. Not very friendly. Involved in With these thoughts Acronis jumped out of bed, tiptoed to the door, opened it and, trying to be some mysterious affairs. She’s the only one getting any letters. Who receives letters nowadays? Postcards quiet, went out of the room and closed the door behind her. Having done that, she hid in the corner at the most. Could she have any reason to dislike the Nigerian girls? Yes! Could she have just made up of the corridor like a hunter lying in ambush, prepared to wait. the story with the letters? She could, actually, but why? If Abangu did it, she could try to get rid of me, Time passed by. Acronis sat curled up in the corner, listening to the silence. Strictly speaking, though it’s going to be quite difficult for her. I’m taller and stronger. Besides, there’re four other girls there was no complete silence. The old building of Finley had its own mysterious life. The floorboards sleeping in the room, and there’s Miss Parfitt’s bedroom downstairs. Miss Parfitt is a light sleeper and were creaking themselves. A window somewhere in the attic slammed shut. The pipes in the reacts to every creaking sound: she will hardly let Abangu get away with strangling me. basement started rumbling. The dishwasher in the kitchen began roaring. The door to Acronis’ Let’s move on to another candidate: Min Qiu — the best pupil in the class. She does Maths and bedroom was still closed. Biology projects — something connected to numerical modeling, — and reads books in Mandarin. After half an hour sitting in the dark, Acronis decided that her plan failed. None of the girls was She isn’t interested in sport, dancing, or theatre and looks quite funny when playing Horatio. Seems to tempted to attack her in the darkness of the corridor. Acronis stood up, stretching her arms and be used to being laughed at though. Min Qiu doesn’t take offense, or just doesn’t show it. Spends hours legs. At that moment the entrance door creaked. Acronis froze. From the corner of the corridor in computer classes — could easily hack the school computer. It’s not clear, though, why she would need where she was hiding, only the edge of the second-floor landing was visible. Acronis noticed a light Abangu’s letters, but she’s clever enough to sort a book cipher out. If she decides to strangle me, it’s going beam running through the balustrade. The sound of careful steps could be heard from downstairs. to be even more complicated for her than for Abangu — Min Qiu is not sporty at all. Then another door creaked. Someone screamed softly. Miss Parfitt? So, who’s left? Carin and Izzy. I don’t know a lot about them. They could finish me off without “Do not be afraid, Miss Parfitt, this is Sergeant Barrow!” a whisper could be heard. “I’m doing a great efforts. Each of them is a head taller than me. These girls spend entire days at sport lessons. round of the school premises. Are you alright?” I don’t know what else apart from sport they are interested in. I can’t believe that those girls are “I’m OK, Sergeant, you can go,” came Miss Parfitt’s disgruntled voice. curious about diplomatic correspondence and the complexities of African politics. I’ll need Carin “If you don’t mind, I’ll take a look around on the second floor. I do apologise but it’s the Chief and Izzy in case I have to call for help. Their beds are next to mine, this is very good.” Inspector’s order.” Having run through all her roommates, Acronis started to think of other girls from their school. “Don’t wake up the girls, for goodness’ sake! They’re having a Math’s test tomorrow,” Miss Parfitt said. Unfortunately, within her first week at Finley she hadn’t managed to get to know all the girls well Footsteps clattered again. Acronis realized that in twenty seconds Sergeant Barrow would be on enough. Except Marie-Rose. She could be included in the list of suspects, as she could have put that the second floor and find her in the dark corner of the corridor. Remembering that she had already scrap of paper into Shelly’s pocket during the rehearsal. But Marie-Rose slept in another dormitory. been one of the suspects of the Chief Inspector after the story with the note, Acronis decided to It’s hardly possible for her to come here at night to kill Acronis. Moreover, she didn’t hear Acronis’ avoid meeting with the police by all means. With one leap, breaking the distance to the door of statement about the criminal’s identity this evening. her bedroom, she turned the knob and jerked the door toward herself. Throwing open the door, Having finished this analysis, Acronis began to tune in to the breathing of the sleeping girls Acronis froze in horror — somebody was standing in the doorway. lying in the neighbouring beds. Some of them rolled over, others were snoring. Acronis heard nothing worrying or unusual. Χ 58 CHAPTER 13 SERGEANT BARROW

Sergeant Barrow was climbing the stairs of Finley House quietly and steadily. From time to time he flashed his torch to the right or to the left. The Sergeant knew that there was not much point to his night duty: in the two hundred years of the school’s existence, not a single serious crime had occurred there. But as soon as Barrow stepped onto the landing on the second floor, a terrible scream pierced the air. The Sergeant shone his torch toward the end of the corridor, to the side, where the girls’ bedrooms were located. The last door was open. Acronis, wearing her pyjamas with white sheep, was standing with her back to the Sergeant. There was a thin, dark-haired girl in pink pyjamas with Mickey Mouse in the doorway. It was Abangu. She was sobbing and looking at Acronis with horror. As the Sergeant was moving towards them, and Miss Parfitt was running up the stairs, bedroom doors began to open, and sleepy girls rushed into the corridor. It was incredibly noisy. Nobody understood what was going on. “Back to sleep! Everybody! Everything is fine!” Miss Parfitt commanded. “Acronis, Abangu, come with me.” The sergeant made sure that, apart from the two frightened girls, no one needed any help from the police. Having given a curious look at the Enigma box, he followed Miss Parfitt, Abangu and Acronis down the stairs. The rest of Finley’s residents returned to their bedrooms.

61 Miss Parfitt sat both girls and the sergeant in the armchairs in the living room, ran into the “I didn’t!” Acronis said resentfully. kitchen and came back with four cups of tea. Abangu had stopped crying. She was staring at Acronis “Calm down, girls,” the Sergeant interrupted them. “And go to bed. I will report the incident to from her chair. The latter in turn was looking at Abangu with dismay. the Chief Inspector. He will want to talk to both of you tomorrow. Miss Parfitt, can they temporarily “So, girls, tell us what you were doing in the corridor in the middle of the night?” Miss Parfitt be placed in different bedrooms?” asked, after everybody had taken a gulp of tea and calmed down a bit. “Yes,” Miss Parfitt nodded. “Acronis, let’s go, you’ll stay with the older girls.” The girls kept quiet. As a result, Acronis spent the rest of the night in a bedroom on the third floor with a fifteen- “Well, stop playing for time. Acronis, you will be the first to tell us what has happened.” year-old girl, Helen, who bravely endured the late night invasion, and even allowed Acronis to use “Well,” Acronis said, “I just went to the toilet, and when I was coming back, in the dark I bumped her wardrobe and chest of drawers. into Abangu. I didn’t expect to see her, so I got scared.” “That’s not true!” Abangu said quietly. Σ “What exactly is not true, Abangu?” Miss Parfitt asked. “Yesterday evening she told us that she knew who had stolen my letters. Later she left the room and didn’t come back for a whole hour. I stayed at the door and listened. I heard some steps and voices. And then the door opened, and I saw her.” “I see,” concluded Miss Parfitt. “Neither of you expected to see each other and that is why you got scared and screamed. Do you have any questions for the girls, Sergeant?” “Yes,” the Sergeant joined the conversation. “Acronis, what were you doing in the corridor for such a long time?” Acronis seemed embarrassed by the question. After a minute of hesitation, she confessed: “Actually, I didn’t know who the criminal was. I hoped it was one of our girls, and that she would follow me into the corridor and try to attack me. Then I would catch her…” “That was very brave but not very wise of you.” The Sergeant shook his head. “Now, Abangu, tell me why you didn’t stay in bed and why you went to eavesdrop at the door?” “Because that night it was the same,” Abangu whispered. “What night?” The sergeant failed to understand. “The night my letters disappeared. Then she left the room as well. There were steps and voices after that. And in the morning my letters were gone.” “Is that true, Acronis?” Miss Parfitt asked. “Did you go somewhere that night?” “Yes, I did,” Acronis confirmed. “But it’s not what you think! I just wanted to turn on the Enigma machine to see how it works. I’ve been doing a project on cryptography.” “She took my letters!” Abangu insisted quietly.

62 CHAPTER 14 THE TELEGRAPH CODE

The next morning awakening was not the most pleasant for Acronis. The thought of the upcoming Maths test filled her with deep dismay. Solving quadratic equations was not one of her favorite activities. Besides, she did not get enough sleep. Fortunately, Helen turned out to be a very nice neighbour. She helped Acronis to plait her hair, and even gave her some stain remover. Chatting merrily, they went downstairs to have breakfast. At breakfast, Acronis tried to sit closer to Shelly but further away from Abangu. While spreading some marmalade on a piece of toast, Shelly whispered into Acronis’ ear: “So, have you told the Chief Inspector who you suspect?” “Not yet…” Acronis immediately got alarmed. “And you? Don’t you have something to tell him?” “What can I tell him?” Shelly wondered. “Maybe…” “What?” Acronis insisted. “Maybe it doesn’t have anything to do with the case,” Shelly lowered her voice, “but I’m sure that Abangu, Naomi, and Victoria knew each other before coming to school.” “How do you know?” Acronis gasped. “Naomi once told me how they had played badminton in their old school in Abuja. They reached the school championship final there. Although they lost in the final. Victoria then added: ‘That happened when Abangu was hit with a racket.’ They both laughed. Then Abangu entered the room, and the girls fell silent.”

65 “When was this?” “A couple of months ago. Shortly before the Easter holidays. Do you think I should tell the Chief Inspector about that?” “Wait,” Acronis suggested, “let’s try to talk to Abangu first. She hates me, but you haven’t Emile Baudot quarrelled with her.” Is a French telegraph operator who “No, I haven’t,” Shelly confirmed, “though I think she hates everybody, not only you.” invented, and in 1874 patented, “It can’t be true!” Acronis said emphatically. “She’s just shy or afraid. Try to get her talking! Come a method that allowed writing up to her today right after the Maths test. Ask if she misses her mum and dad. Maybe she hasn’t letters of the alphabet using sets seen them for a long time. By the way, how often do they come to see her?” of five characters of binary code. The Baudot code was used by ICTIONARY “I think they don’t come here at all,” Shelly said. “Well, I’ll talk to her. What exactly do you want D telegraph operators all over to find out?” the world for many decades. “I don’t know,” Acronis admitted. “I just wish I knew more about Abangu.” She added to herself: “Maybe then I will understand who stole the letters from her and why.” The girls did not have any more time to talk — they had to go to school. At the Maths test Acronis decided to sit next to Min Qiu. Of course, she was not going to sneak peek into her neighbour’s copybook. Acronis tried not to cheat. To some extent, of course. In any case, she felt more confident when she was sitting next to a girl solving quadratic equations at the speed of a Turing electronic computer. The teacher, Miss Ferguson, gave the girls handouts with the test on them. Min Qiu immediately started writing down solutions in perfect handwriting and without a single blot. Acronis quite A binary code easily solved the first equation, made some effort when doing the second, and got stuck with the Is a record consisting of two kinds of characters (for example, dots and third one. The task was to calculate the lengths of the sides of a rectangle with an area of 736 square dashes, plus and minus signs, zeros centimeters, if it is known that one side is nine centimeters longer than the other. After struggling and ones). Programmers call binary for about ten minutes, Acronis sadly looked around. Shelly, Izzy and Carin were still solving the code characters “bits”. Each bit can second equation. Abangu was sitting behind Acronis, her notebook was not visible. Acronis’ glance take one of two values (for example, slipped into Min Qiu’s copybook. The answer had already been written down: 23 and 32 centimeters. zero or one). “That’s what I thought!” Acronis consoled herself and hurried up to write those numbers on her piece of paper. Then she sneaked another look at what Min Qiu was writing just to check. Unfortunately, Min Qiu had already finished the test, closed her copybook and put it on the edge of the desk. Acronis noticed a rather strange column of figures on the cover of her copybook. The column of eight lines consisted of zeros and ones recorded as five numbers in a row.

66 A few minutes later, Miss Fergusson collected the notebooks from the girls and let them go for a break. “I asked Abangu!” Shelly blurted. “It wasn’t so easy. At first, she didn’t want to talk to me at all. But I “Min Qiu, what is it written on the cover of your copybook?” asked Acronis when leaving said that I would like to invite her to visit me during holidays. She didn’t really expect this. In the end, the classroom. she thanked me and said she would love to spend a few days in London, but first she had to ask for “That’s my name,” Min Qiu answered. her dad’s permission. Then I asked: ‘Wouldn’t your mum mind?’ It was very stupid of me because she “Your name?” Acronis did not believe her. “But those are numbers!” answered: ‘My mother died!’ I felt very embarrassed, apologized and ran away.” “No!” laughed Min Qiu. “Those are normal English letters, they’re just simply written in the Baudot binary code.” α Acronis stared at her, puzzled. “It seems that everyone in this school knows something about codes and ciphers. Everyone except me!” she thought. “Well, this is a telegraph code,” Min Qiu explained. “It was invented a hundred and fifty years ago. Each letter corresponds to a set of five numbers — zeros or ones. For example, ‘A’ is 10000, ‘B’ is 00110 and so on.” “How would Acronis be written?” Acronis asked. “Give me a pen and I’ll write it for you,” suggested Min Qiu. Acronis took out a pen and with admiration began to watch Min Qiu writing amazing figures with her beautiful, even handwriting: 10000 10110 00111 11100 01111 01100 00101 When Min Qiu finished, someone pulled Acronis by the sleeve. She turned back and saw Shelly, whose eyes were burning with excitement. “I’ve found something out!” whispered Shelly to Acronis. “Thank you, Min Qiu!” shouted Acronis. Together with Shelly she jumped out of the classroom, crossed the hall, ran through the front door, and out onto a spacious lawn in front of the school building. Having crossed the lawn, the girls hid behind a thick old oak tree growing near the stream and paused to take a breath. “Tell me!” Acronis demanded.

68 CHAPTER 15 MARIE-ROSE BIRTHDAY PARTY

“Listen, Shelly,” Acronis said seriously, having taken a moment to think. “I have to tell you something. Please don’t interrupt.” Acronis gave Shelly a worried look, but Shelly did not even think of interrupting her: on the contrary, she was listening to Acronis with bated breath. “I lied yesterday when I said that I knew who’d stolen the letters. In fact, I haven’t got a clue who did it. But I intend to find it out. I thought it could be one of the girls. It’s quite unlikely that somebody else was able to get into our room, find the letters that Abangu hid somewhere, figure out on the spot where the key to the book cipher was written, tear the piece of paper off and put it in the pocket of your jeans. In theory, of course, it could be done. For example, when we were in class. I believe it was one of us. Either Min Qiu, Izzy, Carin, you, or Abangu herself arranged everything. The only thing I’m sure about is that I didn’t do it.” “So, you suspect me too?” Shelly gasped. “Not anymore!” Acronis calmed her down. “If you were a criminal, you wouldn’t miss the chance to attack me right now, when no one can see us. You could hit me in the head and throw my body into the stream.” Shelly and Acronis simultaneously looked at the cheerful stream that made a loop round the oak behind which they were hiding. “I also suspected you before,” Shelly confessed. “When you reported me to Chief Inspector Loring.”

71 “Did I?” Acronis asked resentfully. “But the note really flew out of your pocket.” Acronis went to congratulate Marie-Rose. Having pushed through the crowd of girls, she opened “Yes, but I didn’t notice it!” Shelly exclaimed. “For a second I thought you’ d made it up to cover her mouth to say: “Happy Birthday!”, but Marie-Rose was the first to speak. up for yourself. Then I realized that you wouldn’t be able to do so many things at once during your “Have you heard what Mrs. Brauhich has come out with?” she asked, almost choking with laughter. very first days at school. You’re a newcomer! You couldn’t know anything about Abangu’s letters. “No,” Acronis admitted. The incident with Naomi and Victoria happened on your first morning at school. You simply “Hold on to your hat!” Marie-Rose advised. “Do you know that in the beginning of July the wouldn’t have time to get to a computer secretly, find the lists of girls, publish them on the Internet, school is arranging a ball for parents?” and so on.” “Yes, my mum said something about it,” Acronis nodded. “Thank you very much, Shelly!” Acronis was genuinely pleased. “I’m happy you don’t suspect “So, Mrs. Brauhich is going to put four harps onto the front lawn and get us to play all the evening!” me anymore.” “The parents will scatter at the first notes!” Izzy predicted, looking over Acronis’ shoulder. “Let’s investigate the crime together!” Shelly suggested. “How will we be able to stand it ourselves?” Carin asked standing next to Izzy. “Sure!” Acronis agreed. “I don’t know,” Marie-Rose replied, “but now we’ll have to do the harp four times a week.” “And what shall we start with?” Getting herself out of the crowd of girls, Acronis bumped into Miss Holly again. Acronis wanted “As my dad says, you should always start with lunch. Let’s go to the dining hall — I could eat to say something nice to her pretty young teacher. Without thinking twice, she grabbed a balloon a horse!” and handed it to Miss Holly: The girls jumped out from the shade of the oak and ran towards an ancient building with high “Look, Miss Holly, this is your photon!” Gothic windows — this was where the school dining hall was situated. “Exactly,” the teacher confirmed, “a particle of light. Do you know what happens when a photon There was a party in the dining hall that day. The paintings on the walls and the lamps under the hits a photo detector? For example, a human eye?” ceiling were decorated with multi-colored balloons and paper garlands. “No, I don’t,” Acronis was confused. “It’s probably someone’s birthday,” Acronis suggested. “Have a look!” Miss Holly said. She took a fork from the table and poked it hard with the ball. There “Yes, Marie-Rose is thirteen today,” Miss Holly, who entered the dining hall after Acronis and was a deafening explosion. The girls who were in the dining hall, as if right on cue, stopped talking and Shelly, said. looked at Miss Holly. Mr. Paul, who had been watching the situation with interest from his great height, “So, there’ll be a cake!” Shelly looked delighted. started quietly clapping his hands. Miss Holly went on to an impromptu physics lesson: At the end of the meal, the teachers closed the shutters, and Mrs. Coppernaum, the head cook of “This is called a quantum measurement,” she explained, as if nothing had happened. “According the school, appeared in the doorway. She brought a silver tray with a huge chocolate cake, decorated to the law of quantum mechanics, the act of measurement changes the object of measurement. To with two candles in the form of numbers: one and three. All the girls stood up and started singing: measure a photon, we must destroy it. Swallow it!” “Happy birthday to you.” When the singing was over and Marie-Rose had blown out the candles, the Saying these words, she picked up a piece of cake with a fork and put it into her mouth. girls queued up for the cake. Mrs. Coppernaum, armed with a long knife, was cutting the cake into The girls watched the performance, stunned. narrow slices. Miss Holly and Mr. Paul were putting the pieces on plates and hanging them out to “Now you understand why the most sensitive information is transmitted with the help of the girls. In the hustle and bustle of the party, Acronis noticed that Miss Parfitt came up to Abangu photons,” Miss Holly continued, quickly swallowing her piece of cake. “To intercept it is the same and gave her a long envelope with a green border. Abangu nodded and immediately ran out of the as to perforate a balloon: if you did it, then the balloon owner would immediately know about it!” dining hall.

72 φ CHAPTER 16 A QUANTUM COMPUTER

In the evening Acronis called Mum. “Are you and Dad going to the school ball?” she asked. “I’m definitely coming,” Mum confirmed. “I have no idea about Dad — ask him yourself.” “That’s terrible!” Acronis sighed. “While you’ll be having fun there, I’ll have to play the harp all the evening.” “Don’t worry about that now,” Mum advised. “The ball is still a long way down the road.” “Ok, I’ll try,” Acronis promised. “Could you transfer twenty pounds to my account, please?” “What? I’ve just sent you fifty!” Mum said. “Yes, I know, but I’ve bought something,” Acronis admitted. “It’s going to be a surprise.” Then she called Dad. “How are you doing, Sunshine?” Dad asked. “I’m fine. Why are you so sad?” Acronis was surprised. “Haven’t you had dinner yet?” “I haven’t even had lunch…” Dad announced miserably. “What’s the matter? Are you ill?” Acronis got worried. “Quite the contrary. I decided to lose fourty-four pounds and run the London Marathon. This morning I went for a run.” “Wow!” Acronis drawled. “And what does Mum think about this?”

75 “I haven’t told her yet,” Dad answered, “but, if you find the right moment, you can talk to her “Yes, I do!” Acronis said. “I need it for a project on cryptography, and for my investigation.” about my plans.” Having finished chatting with Aeneas, Acronis called Dad again. “Good,” Acronis promised. “How are you feeling, Dad?” Acronis asked politely. Having finished talking to Dad, Acronis called her mum again. “I’m fine, thanks!” Dad answered. “Actually, I’m very well. I discovered a long-forgotten feeling: “Mum, I think that Dad is going through a midlife crisis!” she blurted out as soon as Mum the feeling of hunger. A hungry person experiences a wide range of sensations which a person full picked up the phone. of food has never dreamt of”. “To my mind, he’s been going through it for about twenty years,” Mum snorted. “Ok,” Acronis interrupted, “tell me about quantum computers, please.” “Now he’ s decided to prepare for the marathon and lose weight!” “About quantum computers?” Dad was surprised. “But it would not be a quick story to tell. First, “He’ s always trying to lose weight somewhere between lunch and dinner. Anything else to tell we need to understand what a qubit is.” me?” Mum asked impatiently. “And what is it?” “No. Have you divorced yet? “Well, my dear, imagine that you have some strawberry juice and some apple juice, and you mix “Not yet,” Mum replied. “You’d better go to bed.” them together in a glass. This is a quantum bit, and a qubit is the mixed state. A classic bit is a glass “Oh! I remembered what I wanted to ask you!” Acronis exclaimed. “Did you know that Abangu’s containing either strawberry or apple juice, but not both of them. Now, do you understand the mother died?” difference between a quantum bit and a classic bit?” “Recently?” “Yes, I do. It seems to be quite clear,” Acronis shrugged. “No, quite a long time ago.” “Perfect!” Dad said delightedly. “Now let’s mark each glass containing strawberry juice with “I haven’t heard about it.” the number ‘zero’, and each glass containing apple juice with the number ‘one’. A classic bit can “Please, could you find out where, when and how she died,” Acronis asked Mum. “It’s very adopt one of two possible values, of ‘zero’ or ‘one’. A classic computer operates with classic bits. You important. Will you?” enter certain information as a sequence of zeros and ones. It performs some operations with the “I will try,” Mum agreed. “Ok, now, go to bed!” information and gives you an answer also in the form of zeros and ones. Then they are transformed “Good night!” Acronis said and immediately dialed Aeneas’ number. into letters, sounds, drawings, and so on.” “Hi, little pig!” Aeneas seemed happy to hear her. “I’ve ended third today!” “Yes, I know that,” Acronis confirmed. “A letter can be encrypted with several zeros and ones. A “Congratulations! I saw it on the Internet. Try not to fail the qualifying session tomorrow.” telegraph code!” “I’ll try not to! How’re you doing?” “You can encrypt a letter, a sound, a color — whatever you want,” Dad agreed with her. “Now, “Nobody has strangled me so far,” Acronis told him, “but I found out what a telegraph code is imagine that a quantum computer does the same thing. It also receives zeros and ones from you, and how quantum measurements are made.” and then gives you zeros and ones back.” “Good one!” praised Aeneas. “Now you can build a quantum computer.” “So what’s the difference?” Acronis did not understand. “How is a quantum computer different “A quantum computer?” Acronis became interested. “What is it?” from a classical one?” “A hacking machine,” Aeneas said. “It will find keys to all ciphers by using quantum effects.” “The difference is in what is going on inside,” Dad explained. “In a classical computer, zeros and “Something like the Turing Bombe?” Acronis guessed. ones go to and fro. Can you imagine a huge factory where our glasses with apple and strawberry “Well, a modern version of it,” Aeneas confirmed. “If you want to know more about it, ask Dad.”

76 77 juice go along conveyor belts? They appear, disappear, swap places — but never mix. Each glass contains either strawberry or apple juice, nothing else.” “What about a quantum computer?” “It’s the other way round in a quantum computer!” Dad exclaimed. “As soon as our glasses enter the gates of the quantum factory in orderly rows, quantum workers jump at them and begin to mix the juices. Soon there is not a single glass with either pure apple or strawberry juice left.” “Hold on!” Acronis protested. “You said that in the end a quantum computer also gives out only ‘zeros’ and ‘ones’, that is, glasses with strawberry and apple juice. Where does it get them if the workers mixed up the juices in all the glasses?” ICTIONARY

“Good girl!” Dad exclaimed. “The right question. You’ve obviously inherited a scientific mind D from me!” “Actually, I take after Mum,” Acronis cut him off. “Well, go on, please. So, what’s the matter?” “The thing is, my dear, that after the completion of all the operations, the workers put our glasses in a row near the factory gates where the most unbelievable mixtures of two juices are gurgling in the glasses. Before shipping its products to customers, the factory performs another amazing operation with it. It is called quantum measurement. Can you imagine the factory director with a magic wand in his hand passing along the rows of glasses? As soon as he touches the glass with the wand, the mixture in the glass turns into pure strawberry or pure apple juice.” “Yeah!” Acronis was delighted. “This afternoon Miss Holly also talked about the quantum measurement. As an example, she’s stabbed a balloon with a fork.” “Give Miss Holly my sincere admiration, please,” Dad said. “You can do it yourself!” Acronis offered him. “By the way, will you go to the school ball?” “If I am alive,” Dad sighed. “The ball is on the day of the London Marathon.” Having finished her phone calls, Acronis headed to her old bedroom on the second floor. A qubit or a quantum bit However, halfway there, she remembered that she was sleeping on the third floor, in Helen’s room. Is a unit of information in quantum computing devices. The term was coined by Ben Acronis spun on her heel and ran back to the stairs. On the landing, she bumped into Abangu, who Schumacher (USA) in 1995. A qubit can be in any mixture of “zeros” and “ones”. was hopping up the stairs. This time Abangu looked less gloomy than usual. Acronis thought that The most interesting property of qubits is that they can form bound or “entangled” Abangu even seemed to be smiling at something. “A letter!” Acronis remembered. “She’s probably states. A single quantum measurement transforms all qubits of the “entangled” state received a letter from her dad.” into “zeros” and “ones”. Anyway, Abangu did not say a word to Acronis and a moment later disappeared behind the door of her bedroom. τ CHAPTER 17 THE SCHOOL HACKER

Acronis stopped by a computer classroom a few minutes before the rehearsal of “Hamlet” was due to start. Almost all the computers were occupied. The girls were doing projects, presentations, and practicing with training programs. Nobody was speaking, but it was quite noisy in the classroom thanks to the clicking of the keys. Min Qiu, wearing her Horatio costume, was programming something on one of the computers. Mr. Paul was sitting next to her, enthusiastically designing a huge DNA molecule on the screen. Acronis came up to their IT teacher Mr. Davis and asked: “Mr. Davis, how do you hack into a school computer?” “An interesting question, Acronis!” Mr. Davis raised his eyebrows. “Why are you asking?” “I’m trying to get to the bottom of the story about Naomi and Victoria,” Acronis explained honestly. “We know that someone hacked into a school computer and got to know their real names. Could it have been done from here, from our computer class?” “Theoretically, yes,” Mr. Davis said. “To do such an operation, though, you’d have to be an experienced computer hacker. First of all, you would need to create a virtual network connecting one of these training computers with a school computer. Then the hacker would have to enter a password that only teachers know, log onto the school computer and open a file with students’ personal information. The file is protected by another password that is unknown even to me.”

81 “That’s clear!” Acronis said. “It’s too complicated. I would have done it another way. I would have loitered at the door of the school administration, waited for the three women working there to go to the toilet simultaneously, ran to one of their computers and got Naomi and Victoria’s personal details. No passwords would be needed for that. The administration staff work with our data every day: they send out invoices, our marks for tests and so on. I don’t think it can be difficult at all to find an open file with our data on the screen of one of the computers.” “Quite logical,” Mr. Davis agreed. “Although it’s hard to imagine all the ladies from our administration department going to the toilet at the same time and leaving confidential information open on the screens of their computers.” ICTIONARY

“That’s right!” Acronis agreed. “Then, probably, something unexpected happened in the school D hall. Something that made all the ladies jump out of the office. Maybe someone called for help. I have to discuss this with Chief Inspector Loring!” With these words, she left the computer classroom and went to the school theater, where Miss Sikorsky was already grumbling: “Acronis and Min Qiu are late again.” “We are here, Miss Sikorsky!” Acronis shouted, running into the hall. Min Qiu sneaked in after her. “Since you are here,” Miss Sikorsky said sternly, “would you be so kind as to start. Act 2, Scene 2. Hamlet, Rosencrantz and Guildenstern. Abangu, Marie-Rose, onto the stage! Ready… Steady… go!” “My honoured lord!” Abangu said in a bored voice. “My most dear lord!” Acronis smiled widely. “My excellent good friends!” Marie-Rose greeted them both. “How dost thou, Guildenstern? Ah, Rosencrantz! Good lads, how do ye both?” “Happy, in that we are not over-happy,” Abangu answered quite confidently. “On fortune’s cap we are not the very button.” At that very moment the door of the theater opened and the school’s Headmistress appeared — the formidable Mrs. Jellicoe. The girls fell silent. “Sorry, Miss Sikorsky,” the Head said anxiously, “I have to talk to Abangu and Acronis. It won’t Hacker take long. Continue without them, please.” Is a computer criminal. On the Internet, hackers penetrate into other people’s “That’s fine,” Miss Sikorsky said calmly. “We will repeat Act 4, Scenes 5 and 6. Queen, Horatio, start!” computer systems and steal sensitive information: bank codes, letters, etc. Acronis and Abangu followed the Headmistress silently. Acronis glanced at Abangu, but she kept looking at the floor in front of her. They crossed the hall with its marble columns and entered

82 Mrs. Jellicoe’s office. Chief Inspector Loring, Sergeant Barrow and Miss Parfitt were already waiting “You were at school the week before last, weren’t you? I wasn’t here then.” for them. After greetings, Mrs. Jellicoe invited everyone to sit down. As all the chairs were occupied, “Yes, I was,” Helen nodded. Acronis and Abangu sat on the leather sofa, and Abangu tried to move away from Acronis as far as “Do you remember what happened right here in the hall? Something unexpected and terrible possible. Mrs. Jellicoe started speaking. that frightened everyone?” “I am dissatisfied with you, girls!” she announced. “I have been told that you walk around the “Do you mean the Aruk Matan case?” Helen suggested. school at night, and that recently you have woken up the school with your shouting. Miss Parfitt “Yes,” Acronis snatched at her words. “What was it? Tell me, please.” says that Acronis is trying to catch the person who has stolen Abangu’s letters. Abangu accuses “It happened two weeks ago on Thursday,” Helen began. “The girls were coming out of classes Acronis of stealing her letters. I want Acronis to stop playing the private detective immediately. for the long break. Suddenly, someone screamed. The teachers came to the cry; almost the whole Abangu must apologise to Acronis for her unfair accusations.” school gathered. I ran with everyone else. I saw huge red letters on the floor of this hall. They “She’s a newcomer,” Abangu said without raising her eyes. “Dad wrote that I was in danger. That looked as if they were written in blood. The letters were clumsy and large. Then I thought that it there was a threat from someone who had not been at our school before the last holiday. I don’t was probably not blood, but red paint. Still, it was strange… and a little scary. Mrs. Jellicoe made know if that was her who stole the letters, but I’m afraid of her!” everyone go out of the hall and immediately ordered to wash off the words.” “I am sure that Acronis does not threaten you with anything, Abangu!” the Head urged her. “On “What was written there?” Acronis kept badgering her. the contrary, she is trying to help you. We also want to help you. Therefore, you should stay here a “I’ve told you: Aruk Matan.” few more minutes. Acronis, you may go!” “What is Aruk Matan?” Acronis could not calm down. “Can I ask you just one question, Mrs. Jellicoe?” Acronis begged. “It’s a long story. I’ll tell you this evening. Now, I need to hurry to my German lesson!” Helen “A question?” The Headmistress frowned. “Well, go ahead. Be quick, though.” waved and ran away. “Can you remember if something unusual or even horrifying happened in the hall near the door of your office about ten days ago?” Ζ Mrs. Jellicoe was obviously not ready for such a question. Before answering, she exchanged looks with Miss Parfitt and the Chief Inspector. Then she said: “Nothing you need to know about, Acronis. Go to class!” “Thank you very much.” Acronis politely said goodbye and ran out of the Headmistress’s office. She was excited: judging by Mrs. Jellicoe’s answer, something definitely happened. So, her theory was confirmed. Now, she just needed to find out the details of the incident in the hall, when the computers in the administration office had been left unattended for a few minutes. Acronis wanted to talk to someone who had been at school a few days before she joined. At that moment, the door leading to the lawn opened and her new roommate Helen came in. Without thinking twice, Acronis ran up to her and said: “Listen, Helen. I want to ask you a very important question!” “About what?” Helen wondered.

84 CHAPTER 18 DOUGHNUT

That evening, as soon as Acronis took out her phone from Miss Parfitt’s basket, the phone rang. “Yes, Mum?” Acronis answered. “Are you trying to drive me mad?” Mum asked angrily. “What do you mean?” “Was it you who bought the terrible ginger cat that was delivered today?” “Yes, it was me…” “Has it ever occured to you that children can’t buy pets without their parents’ permission?” “But this is for you and Dad for your wedding anniversary…” Acronis said sadly. “I wanted it to be a surprise for you both.” “Very kind of you,” Mum grumbled. “Hasn’t it ever occured to you that somebody will have to feed the cat, let it outside, comb it, and wash its rugs? Do you really think Dad can handle it?” “I think that Dad likes cats,” Acronis said, “and you can do the rest.” “Never buy any animals again!” Mum said strictly. “No cats, no mice, no crocodiles! Do you understand?” “Yes, I do…” Acronis agreed gloomily. “I ordered sixty cans of cat food from Harrods for your cat and a special heated mat that will keep a comfortable temperature,” Mum said in an unexpectedly calm tone. “So you’re not angry?” Acronis beamed.

87 “No, the cat is quite cute. What name do you want to give it?” Mum asked. “And to the UK too?” Acronis asked the question which had been worrying her. “Shall we ask Dad?” Acronis suggested. “He’s very imaginative.” “I hope not,” Dad tried to calm her down. “So far, they have attacked only African countries: “So, he will come up with some strange name, something like Beelzebul,” Mum said sarcastically. Niger, Chad, Cameroon…” “I’ve been calling him Doughnut so far.” “They kidnapped my friend’s mum,” Acronis said. “Will you let me know if you hear anything “I like the name Doughnut!” Acronis was delighted. “Tell me, please, did you have a chance to else about them, ok?” learn anything about Abangu’s mother?” “Of course, I will, Sunshine,” Dad promised. “Yes,” Mum said, “she didn’t die. She was kidnapped last year.” After speaking to Dad, Acronis called Aeneas. “Kidnapped?” Acronis was terrified. “By whom?” “So, how did the qualifying session go?” she asked first. “By some terrorist group called Aruk Matan. There’s very little chance Abangu’s mother is still alive.” “Perfectly!” Aeneas responded. “Johnny is second quickest, I am sixth. On Sunday we will fight “Aruk Matan?!” Acronis exclaimed. “I have to call Dad urgently.” for the podium.” “Tell him about Doughnut too,” Mum said, and hung up. “Congratulations! Do you know why Dad talked to a lawyer?” Acronis dialed Dad’s number. “No, I don’t.” Aeneas answered. “Probably, because of the divorce.” “Speaking,” Dad answered formally. “Listen,” Acronis said sternly. “There won’t be any divorce. I won’t let it happen. Word of Acronis!” “Dad, it’s me!” Acronis cried. “Well, if you say so, then I’m completely calm,” Aeneas said ironically. “Oh, I’m sorry, Sweetheart! I’ve just been talking to my lawyer,” Dad tried to justify his official tone. “Look, this is what I wanted to ask you,” Acronis changed the subject. “Once you told me that “Mum asked me to tell you that I gave you a cat called Doughnut for your wedding anniversary, Johnny’s parents lived near our school…” and now you have to take it for a walk every day,” Acronis added creatively. “Yes, in Macintosh Manor, which is a five-minute drive from your school.” “Really?” Dad seemed interested. “Well, I’m up for that. Walks are very good for losing weight.” “Great. Tell Johnny that I’ll call him if I’m in danger.” “Ok, Dad, how about discussing how you can lose weight a bit later? Now, tell me everything you “Why should you be in danger?” asked Aeneas. know about Aruk Matan.” “Because I got into a fight with the terrorist sect Aruk Matan!” Acronis said firmly and hung up. “Aruk Matan?” Dad was surprised. “It’s strange that you are interested in such a terrible On her way to the third floor, Acronis met Miss Parfitt. organization. It’s one of the bloodiest terrorist groups of our time. Thousands of people had their “Acronis, if you want, you can return to your bedroom on the second floor,” Miss Parfitt said, lives taken by these terrorists. Several years ago, they raided a school for girls in Nigeria and took smiling. “Abangu is no longer afraid of you. I hope you are not angry with her and will behave tactfully”. two hundred and seventy female students into slavery.” “Thank you, Miss Parfitt!” Acronis was delighted. “I will take my stuff back tomorrow morning.” “In Nigeria?” Acronis asked. “This means that Aruk Matan operates in Nigeria?” Acronis did not tell Miss Parfitt that she wanted to ask Helen about the incident with the “bloody” “Yes,” Dad confirmed. “It’s a secret society or a religious sect founded in 2002 in the Nigerian city inscription. Before going to sleep, she waited for Helen to get into her bed, and then asked her: of Maiduguri. The leaders of Aruk Matan believe that everyone should live according to medieval “Do you remember who was the first to discover the inscription Aruk Matan? Who screamed Sharia law, and ruthlessly punish those who want to live differently. They destroy everything when seeing it?” connected with Western culture or science. It is even forbidden to wear trousers and say that the “I reckon it was one of your girls,” Helen said. “Naomi or Victoria.” Earth is round. The worst thing is that Aruk Matan already controls half of Nigeria, and the tentacles “I thought so,” Acronis nodded. “They are from Nigeria. They must have known about the Aruk of the sect stretch far beyond the borders of the country.” Matan sect and were afraid of it.”

88 89 “Probably,” Helen agreed. “Later Mrs. Jellicoe told us that Aruk Matan kidnapped some school girls. The American President and our Prime Minister then promised to do everything possible to find and release the girls. Maybe, right now in the Maiduguri jungle, agents of MI6 are looking for secret bases of terrorists.” “MI6?” Acronis became interested. “I guess I have heard of it. Does it have anything to do with spies?” “Yes, it is. This is the most secret of all our secret services,” Helen said. “MI6 employees call their organisation ‘The Circus’. I’ve read that the director of the Circus signs their letters with one letter ‘C’. Only the Prime Minister knows their real name.” “Great!” Acronis sighed. “I would like to become a secret agent and fight terrorists…” ICTIONARY

“Maybe one day you will receive a letter from the Circus,” Helen suggested. “They can invite D anyone to work for them — even a pupil!” “How can I be of any interest to them?” Acronis was talking to herself. “Well, I know a thing or two about ciphers. But I think this is not enough…” Saying this, she comfortably curled up in her bed and fell asleep. ϊ

MI6 Is a department of the British Secret Service that conducts secret operations abroad. The activities of MI6 are shrouded in mystery and connected with many legends. It is known that the MI6 agents delivered to Britain the first Enigma machine captured from the Germans. MI6 agents were engaged in the decryption of the German ciphers at Bletchley Park. The first computers were created with their participation. CHAPTER 19 A CHARITY WALK

The next morning Mrs. Jellicoe made the whole school go for a charity walk. The girls were allowed to wear jeans and T-shirts. Several parents, carrying heavy picnic backpacks, joined the procession. The lanky Mr. Paul, who was wearing his funny green hat, was leading the column. Sometimes he stopped to wait for the stragglers. Acronis was walking next to Shelly, telling her friend in a low voice everything she had learnt about Aruk Matan the day before. Shelly gasped in surprise when she learnt that Abangu’s mother had been kidnapped. “Now I understand why Abangu’s come to our school,” she whispered, looking around. “Her dad must have sent her to England to hide. And now, after the story with the inscription, she is afraid that ‘Aruk Matan’ has found her.” “Yes,” Acronis said. “I also think so. She said that she’ d received a warning from her dad that some terrible person had appeared at the school recently, after Easter holidays. She thought it was me.” “I’m not surprised,” Shelly nodded. “Very few pupils change schools on Easter holidays.” “Do you know anyone apart from me? Other newcomers?” “No…” Shelly shook her head. “Definitely not in our class. Maybe in senior school? I can’t say I know everyone there”. “I’ll ask Helen,” Acronis thought.

93 At this point, the girls reached the bridge over a stream and stopped to admire the fast and clear water, through which the grassy bottom could be seen. “Look at this trout!” Shelly exclaimed. “Keep moving, girls!” Miss Parfitt hurried them up. “We have three more miles to go.” Holding hands, Shelly and Acronis ran forward. Overtaking the crowd of senior school girls, they went to the head of the column. Acronis noticed Miss Holly and came up to her. “Miss Holly,” she began, “Dad told me about a quantum computer.” “Did he?” Miss Holly sounded interested. “You know what a qubit is, then?” “Yes, it’s quite simple,” Acronis said, “and I realized that the quantum computer is something like ICTIONARY

the Turing Bombe: it’s meant to decrypt ciphers.” D “You could say so,” Miss Holly nodded. “I don’t understand just one thing. If there are so many devices for cracking ciphers and codes, how do all banks, secret services, diplomats and so on cope with this? Have they already put up with the fact that anyone can read anything?” “Good question!” Miss Holly was delighted. “In fact, banks are not in such a bad situation. First, the quantum computer hasn’t been built yet. So far, this’ s been only a concept, or a mathematical model, if you want. Secondly, there are ciphers that are theoretically impossible to decode.” “What kind of ciphers?” Acronis was curious. “The Vernam Cipher, for example,” Miss Holly said. “It was used during the Cold War for the communication between the Soviet Union and the United States of America. The key to this cipher The Vernam Cipher is a random sequence of letters. An ideal key should have had the same number of letters as in the Is still considered to be one of the most reliable methods for encrypting radio encrypted message.” messages. The letters of encrypted messages are entered in binary code. Each of the 32 letters of the alphabet used, corresponds to a sequence of five characters (0 or 1, “Wow!” Acronis chuckled. “Such a long key!” as in the telegraph code). Each of the letters of the key is also indicated by five binary “This is just one of the problems,” Miss Holly said. “In the twentieth century, encrypted notebooks symbols. were used. Just two copies of such notebooks were printed. There was a random sequence of letters An encrypted message is generated by comparing the text and the key characters. on each page — too long to serve as a code for one message. Before a communication session, two If the characters match (0 and 0, 1 and 1), 0 is written to the encryption. If they differ radio operators agreed which page of the notebook they would use. Then the operator transmitting (0 and 1, 1 and 0), 1 is written to the encryption. In the same way, the message is the message typed the text on the keyboard of the encryption machine. After each letter of the text, decoded: the key works both directions. The reader can easily verify that this is true he entered a letter of code. The machine formed the letter of the encrypted message from these two by trying to encrypt and then decrypt a short sequence of “zeros” and “ones” with the help of a different sequence of “zeros” and “ones”. letters and transmitted it to the air. At the other end of the communication line, the operator receiving the message repeated the operation, entering the received message letter by letter into his machine.

94 After each received letter, he entered a code letter. As a result, the encryption machine gave him the text of the original message. At the end of the communication session, both operators had to take the used pages out of their notebooks and burn them.” “And such a cipher can’t be decoded?” Acronis said with surprise. “That’s right,” Miss Holly said, “if the sequence of letters is random and if you don’t have a copy of the notebook, then you can’t do anything with it. As you see, the whole procedure of sending messages is rather inconvenient.” “Besides, even if a spy gets a copy of the notebook, all these tricks won’t work,” Acronis stated authoritatively. “That is why the most reliable lines of secret communication are arranged in a different way these days!” Miss Holly summed up. “What way?” Acronis asked. “The messages are transmitted with the help of quantum key distribution,” Miss Holly began, but she had to interrupt her lecture at the most interesting point. Mr. Paul waved his hand, and the procession stopped — it was time to have a picnic. Acronis was so involved in the conversation that she almost did not look around. Now she discovered that they had reached a picturesque valley stretching between two hills. Sheep were grazing on the slopes of one of the hills. A stream was running along the bottom of the valley. Probably, it was the same one, which Acronis and Shelley admired from the bridge at the beginning of the walk. At this place it was quite shallow, and it was possible to walk across it. Acronis and Shelly took off their trainers and stepped into the cold water. The teachers and parents were laying tablecloths on the grass and taking food out of their bags. Miss Holly and Miss Parfitt began handing out sandwiches to the girls. Suddenly, a little song, once made up by Dad, came to Acronis’ mind:

“Oh, where do we wend our way Along the twining road? What is the price we have to pay Apart from a sore throat?” Φ

96 CHAPTER 20 THE BULLDOZER

Acronis got out of the stream, put her trainers on and joined the queue for a sandwich. She was at the back of the queue. The girls who had already received food scattered about the valley. Acronis noticed that Abangu climbed almost to the top of the hill, chose a large round stone and sat down on it with her sandwich. “Miss Parfitt wanted me to behave tactfully,” Acronis told herself. “Would it be tactful to join Abangu in her eagle’s nest? I think it would!” So, Acronis began to climb the slope of the hill, and in two minutes she was standing in front of Abangu. “Listen,” Acronis began with her most friendly intonation. “I knew nothing about Aruk Matan until yesterday. And I didn’t know about your mum. I’m really very sorry that it all happened. I hope you are not frightened of me anymore?” “No,” Abangu answered, “I’m not afraid of you now. Mrs. Jellicoe told me that you’ve never been to Africa.” “That’s true,” Acronis nodded. “Never, but I’d really like to go there. How is it there, in Africa?” “Scary,” Abangu said looking down at her feet. “When some burly men in a big black car came and took my mum, I was terrified.” Acronis did not know what to say. After a pause, Abangu continued.

99 “Our chauffeur was nearby, but he didn’t help. There were some other people — some officials, “They are building a tennis court,” Min Qiu added. and even a minister. Nobody did anything.” “How long have they been working here?” Acronis asked. Abangu was silent again. Acronis looked around in confusion. At the bottom of the hill, the “I don’t know… Maybe for a week?” Shelly suggested. school picnic was carrying on. Sheep were grazing on the opposite side of the valley. Further beyond, Within seconds, they were at the doorstep of Finley House. Shelly put her right forefinger to the behind a grove, there was a school pitch for sports competitions. A bulldozer was working on a sensor, the door lock clicked, and the wet girls finally got into a dry and warm room. tennis court which was being constructed. The cozy English landscape did not coincide with the “Change clothes, girls!” Miss Parfitt’s voice came from the kitchen. “We’re having tea in the living dark story told by Abangu. Acronis decided to continue their chat and express her support. room in five minutes. Min Qiu, how is your foot?” “I can imagine how you felt when you saw the words ‘Aruk Matan’ written in blood in our school!” “It’s all right, Miss Parfitt!” Min Qiu answered and limped up the stairs. Acronis said with sympathy. “Unbelievable! Who might have done it?” Acronis went to the fireplace in the living room. Someone had already lit the fire. The wood “I don’t know,” Abangu cut her off, jumped to her feet and ran down the hill. was cracking cozily. Warming her hands at the fireplace, Acronis recalled the ominous words of Overwhelmed by such a reaction, Acronis swallowed the rest of her sandwich and also walked Abangu: “Burly men in a black car.” down to the valley. The picnic was coming to an end. Parents and teachers were packing up their backpacks. Mr. Paul was looking anxiously at the sky, which was covered with grey clouds. It was θ time to go back to school. As soon as the girls come together and set off the first drops of rain fell down to the ground. “We are leaving! Be quick!” Miss Parfitt was hurrying up the girls. As ill luck would have it, Min Qiu tripped on a stone and hurt her foot. Acronis and Shelly volunteered to help her. Holding the clumsy Min Qiu under her arms, they walked at the end of the column, lagging behind more and more. Miss Parfitt constantly ran between them and the main group. When the school buildings loomed ahead, it was already raining hard. Water was squishing in Acronis’ trainers. “I’ll run ahead and put the kettle on!” Miss Parfitt called out to them, when Finley was no more than a hundred yards away, and rushed forward. Acronis, Shelly and Min Qiu turned onto a path that led past the unfinished tennis court. “We’ll take a short cut!” Shelly explained. When they were passing by the bulldozer, Acronis suddenly felt worried. After a second, she noticed two burly men hiding under the bottom of the bulldozer. They had dirty faces and hands. They were laying flat down on the ground, and Acronis thought they were watching the girls limping along in the rain. “Who are they?” Acronis asked Shelly and Min Qiu. “Workers,” Shelly shrugged.

100 CHAPTER 21 ARUK MATAN

After lunch, Acronis decided to start working on her cryptography project. She took a big copybook and opened it on a clean spread. On the left-side page she wrote: “What I know,” and on the right page: “What I don’t know.” Having finished with the headlines, Acronis started filling the pages with terms and phrases in the order they were coming to her mind. She wrote on the left: “’Enigma’ is a cryptographic machine. Turing Bombe is a decryption machine, the first computer. The book cipher. Aeneas Tacticus. The Caesar cipher. The telegraph code — letters marked with ‘zeros’ and ‘ones’. The Vernam cipher — can’t be broken unless the key is stolen. A photon — a particle of light. Photons are used for encryption. Quantum measurement. Quantum computer — good for decoding ciphers.” Acronis thought for a bit, and then started making notes on the right page. So, some questions appeared on it: “How do hackers steal the keys? What is the quantum code distribution? What is the role of photons here? What happens in the process of quantum measurement? How to get one juice from a mixture of two juices? How to build the quantum computer?” Acronis decided that there were enough questions, drew her cat Doughnut on the right page and closed the copybook. Looking at her watch, she saw that the car race, in which Aeneas had taken part, must have been finished. Acronis quickly went down the stairs and knocked on the door of Miss Parfitt’s office. Having been welcomed, she opened the door and saw Miss Parfitt and Abangu, sitting on the couch side by side. There was an envelope with a green border in Abangu’s hands.

103 “What do you want, Acronis?” Miss Parfitt asked. “Hurry up, Acronis! Everyone is waiting for you,” she said in a dissatisfied tone. “Can I get the phone?” Acronis had to interrupt their conversation and went outside together with Miss Parfitt. In the “Of course,” Miss Parfitt nodded and added, “my congratulations to Aeneas — he is on the street the girls were lined up in pairs already. Acronis stood next to Shelly. podium today!” “I’m singing solo today!” boasted Shelly. “Is he?” Acronis gasped. “Has he won?” “I’m glad!” smiled Acronis. “Listen, I understand nothing — absolutely nothing!” she said suddenly. “He came third. Johnny Macintosh is the winner”, Miss Parfitt reported. “What are you talking about?” Shelly was curious. Acronis grabbed her phone and ran out into the corridor. It was pointless to call Aeneas at that “Abangu’s just told me that it was her who had written ‘Aruk Matan’ and stolen the lists of pupils. moment, so she dialed Mum’s number instead. She can be expelled from the school for that!” “Mum, is Aeneas on the podium?” she shouted as soon as Mum picked up the phone. “You mean that Chief Inspector Loring has exposed her?” Shelly gasped. “Yes, he is. Johnny has just been showering him with champagne,” Mum replied. “Next Sunday “It seems like she’s confessed,” Acronis suggested. “I saw her talking to Miss Parfitt.” all of us are going to visit you.” “But why would Abangu do this? Who stole her letters, then?” “What about Dad?” “No one?” Acronis was thinking aloud. “Maybe she’s just been lying?” “Dad is going to take us to some Japanese restaurant. Tell him, please, that this isn’t a good idea,” “But why?” Shelly did not get it. Mum said. “It looks like there’s no reason,” Acronis agreed. “I think, the fear of ‘Aruk Matan’ makes her do “I’ll try. How’s Doughnut doing?” very strange things.” “He’s already eaten six servings of cat food. He obviously prefers Norwegian salmon.” “Let’s talk to her after church!” Shelly suggested. “He has great taste!” Acronis admired. “Well, I have to go to the church. Give Aeneas my “Great idea!” Acronis agreed. congratulations!” Although, when the girls came back after the church service, Abangu was not in the room. Her Acronis hung up the phone and rushed to her bedroom to change into her school uniform. The things also disappeared. The pajamas, the volume of Shakespeare, her parents’ photos, and the toy bedroom was empty. Carin, Izzy, Min Qiu and Shelly were ready to go. With other girls they were lion she slept with were not in sight. Acronis and Shelly ran around the house, but found no trace standing on the landing chatting about something. Acronis pulled her clothes out of the wardrobe of Abangu. In the end, they went down to Miss Parfitt and asked: and started changing frantically. At this moment, Abangu entered the room. She walked slowly to “Miss Parfitt, where is Abangu? We can’t find her!” her bed and sat on the edge. Acronis noticed that she was still wearing jeans and some sort of dark “Abangu is spending this night at Mrs. Jellicoe’s,” Miss Parfitt said. long-sleeved shirt. “But why?!” Shelly exclaimed. “Why aren’t you dressing up?” Acronis asked. “Is it true that she will be expelled from our school?” Acronis added. “I’m not going to the church,” Abangu answered and added after a short pause, “maybe I’ll be “Girls, I can’t tell you anything on this matter,” snapped Miss Parfitt. expelled from school.” Acronis and Shelly had to go back to their room without finding out anything new. “How come? Why?” Acronis could not believe it. “That was me who painted ‘Aruk Matan’ on the floor and stole the lists of pupils,” Abangu said calmly. δ “You? Why did you do it?” Acronis was stunned. There was a knock at the door. It was Miss Parfitt.

104 CHAPTER 22 QUANTUM MEASUREMENT

Although she kept thinking about the mysterious story of Abangu, Acronis did not miss the opportunity to phone her dad and ask a few questions about cryptography before going to bed. “Dad,” she began. “Can you tell me something?” “Of course, Sunshine.” “Miss Holly said that the best way to protect the key to the cipher from hackers is the quantum distribution of the code. Though, she didn’t have time to explain what it was. Could you tell me?” “I’ll try,” Dad agreed. “As far as I remember, Miss Holly told you that photons were like balloons.” “Yes, she did,” Acronis confirmed. “Then imagine that you have two balloons connected by a long rubber tube. You’re sending one balloon to Aeneas, and you’re leaving another one to yourself.” “OK,” Acronis nodded. “Let’s suppose that Aeneas, like Miss Holly once, takes a fork and bursts his balloon. Tell me please, what is going to happen to your balloon?” “The air from my balloon will go out and my balloon will deflate too,” Acronis said. “That’s right!” Dad was delighted. “It means that, if Aeneas makes a quantum measurement, both of your balloons-photons will simultaneously move into a new state. Photons that behave like balloons which are connected by a tube are called entangled. By measuring one of the entangled photons, you will change the state of the other, even if they are very far from each other.”

107 “And what?” Acronis asked impatiently. “What does it have to do with the quantum distribution of a code?” “A lot,” Dad answered. “If you transmit your code, the key to the cipher, to Aeneas, using entangled photons, you can be absolutely sure that you will immediately know, when some hacker tries to intercept them. As soon as the hacker punctures a stolen balloon, the balloon in your hands will deflate as well. You’ll call Aeneas and ask if he’s done it. Aeneas will say that it is not him! Then you’ll take another code out of your pocket and send it to Aeneas using another pair of balloons. You will do so until you make sure that the sent balloon has been burst by Aeneas, and not somebody else.” “I see,” Acronis agreed. “There’s still something I don’t understand though. How do the balloons ICTIONARY

correspond with all the ‘zeros’ and ‘ones’ which make up the code? Will you tell me about it tomorrow? D It’s time to finish with phone calls now, and I still have to call Aeneas. Bye Dad.” Having hanged up on Dad, Acronis dialed Aeneas. “Did you watch the race, little pig?” Acronis heard the excited voice of her brother. “No, at this time we were on a charity walk!” Acronis explained. “It’s a pity, I moved from sixth to third!” “Yes, I know you did well!” Acronis praised him. “Listen, I have very little time now.” She stopped Aeneas’s attempt to continue talking about the race. “Mum said that three of you are going to visit me next Sunday.” “Yes, but I’m afraid it’ll not make you very happy,” Aeneas interrupted her. “Why?” Acronis did not understand. “Because Mum and Dad are going to tell you about their divorce and explain, when and who you will be living with.” “No!” Acronis shouted. “I don’t want to live with anyone! I want to live with everyone together! And what about Doughnut?” Quantum key distribution She burst into tears. Is a key method of protecting encrypted messages using quantum cryptography. “Oh, dear! Don’t cry, please,” Aeneas tried to console her. “Maybe they will change their mind. The method is based on the theorem on the impossibility of quantum cloning. According to this theorem, no hacker can make a copy of the quantum state sent by It’s still a whole week until Sunday.” Acronis to Aeneas. Thus, if Acronis and Aeneas own the halves of the entangled state, But Acronis couldn’t help crying. She said something unintelligible, then hung up and went to they can be sure that no one will measure this state without their knowledge. her room, smearing tears with her fist. “What’s the matter? What happened?” asked Shelly. All the girls gathered around Acronis trying to console her. Acronis got under her blankets and did not answer their questions. Then Miss Parfitt came and brought some tea. Acronis did not get out of the blankets. She kept crying until she fell asleep. ∞ CHAPTER 23 IN THE TOWER

On Monday, the most difficult subjects for Acronis followed each other — Latin, Maths, French, Biology. At the Biology lesson Mr. Paul proudly demonstrated how the code written by Min Qiu worked. It allowed to construct DNA of different animals out of a variety of genes. The girls got homework — to study the properties of rats’ DNA. It was a hard day. Abangu, as if nothing had happened, came to school together with everybody. The girls were too busy to ask her about the night spent at Mrs. Jellicoe’s, the red stained encryption of Aruk Matan and other interesting things. The lesson was over at last. Tired and hungry, everybody headed to the dining hall. “Miss Holly, I know what the quantum key distribution is,” Acronis boasted when she saw her Physics teacher in the crowd. “Great, Acronis!” Miss Holly said. “Come to me after lessons, I’ll show you something interesting.” Acronis nodded. Then, carrying a tray with food she moved towards a table occupied by Shelly. “Listen,” Shelly whispered to her. “I talked to my mum. She’s a psychologist specializing in divorce. She promised to invite your parents to our house. When they come, she’ll try to understand why they’re going through a divorce and what should be done to avoid it.” “Thank you very much!” Acronis looked at Shelly with appreciation. “Maybe your mum will manage to sort it out. I don’t know what to do.” Marie-Rose came up to the girls.

111 “Do you remember that we’re having a harp lesson after lunch?” she asked Acronis. hole appeared in the blind covering the western window. A narrow ray of sun came to theroom “Oh my God!” Acronis groaned. through that little hole. Acronis saw a sunbeam on the polished surface of her teacher’s desk. Shelly gave her a sympathetic look. “We’re lucky that the weather is nice today,” Miss Holly said. “Please, hold the base of the “And I’m having a fencing lesson with Mr. Marshall,” she said. Acronis was jealous. spectrograph tightly so it’s not moving across the desk.” “Have you heard that we’ll have Ophelia and Polonius again?” Marie-Rose continued to share Miss Holly installed the instrument so that the ray of light fell on a glass prism. Acronis firmly news with the girls. “Two newcomers — Olivia and Esme. They came from the Winchester school.” pressed the wooden base to the desk, and Miss Holly began to turn a large copper screw, which was “Newcomers?” Acronis was curious. She immediately remembered about Abangu and looked changing the angle of one of the tubes. Acronis watched with admiration how the tube was slowly around to find her. Abangu was sitting at the corner of the table and eating an apple. Having finished leaning towards the sunbeam. For a few seconds it blocked the path to the prism, but then it stood chatting with Marie-Rose, Acronis came to Abangu. exactly in the position Miss Holly wanted: the sunbeam now fell inside the tube, ran through it and, “Hi,” she said. “So, you’re not expelled, are you?” as before, lit the prism. “No,” Abangu answered gladly. “Mrs. Jellicoe forgave me. She’ll write to my dad, though.” “Done!” Miss Holly exclaimed victoriously. “Now, I will hold the spectrograph, and you look “Will you come back to our room?” Shelly, who joined the conversation, asked. into the eyepiece of the visual tube and rotate the second screw very slowly.” “Yes,” Abangu nodded. “I’ll move my things back after lessons.” Acronis went to the second copper tube, which, like the first one, was aimed at the prism with The girls said goodbye to each other. Acronis went to her harp lesson, Shelly ran to the sport hall, one end. Carefully holding it with her fingers, Acronis put her eye to the eyepiece located at the end and Abangu went to the computer class. of the tube opposite the prism. Suddenly, she saw a round red spot. Two harp lessons with Mrs. Brauhich seemed to be incredibly long for Acronis. Music exercises had “Well, what can you see?” Miss Holly asked her impatiently. never been so hard for her. Mrs. Brauhich was not satisfied and asked Acronis to repeat again and again. “I see a red spot,” Acronis reported. “There’re just two months left until the school ball,” she said shaking her head. “You have to do “Well. Now turn the screw.” a lot of work. Don’t slack!” Acronis started rotating the screw that adjusted the inclination of the visual tube. The red spot, Finally, the bell rang ending Acronis’ suffering. which she continued to look at, through the eyepiece, began trembling and changing its color. First “Goodbye, Mrs. Brauhich,” Acronis muttered, put her music notebook into her backpack and it became orange, then yellow, then green… ran to the Physics classroom. “It’s a rainbow,” Acronis guessed. This room was special. It was located on the top floor of the school in the little tower. Miss “Exactly,” Miss Holly confirmed. “At first you detected red photons, and now you probably see Holly called it “belvedere”. Its windows overlooked the west, the east and the south. Everything green ones.” happening on the vast school territory could be seen through them. “Yes, I do,” Acronis confirmed, “the light has changed to green, and now it’s blue.” “Come in, Acronis!” Miss Holly greeted her. “Look at that.” “That’s right,” the teacher commented. “By changing the angle at which you are looking at the She showed the girl an old instrument with two long copper tubes, fixed on a wooden stand. prism, you can select photons of a certain color.” There was a big beautiful prism between the tubes. “Is this the quantum measurement?” Acronis asked. “You’ll see what the light consists of,” the teacher promised. Acronis did not understand what she “No,” Miss Holly laughed. “This is the classic measurement. Using this instrument, a spectrograph, had to do, so she waited. Miss Holly came up to each of the windows in the room and put down the scientists began to study the physics of light two hundred years ago. But I will tell you about quantum blinds. It became dark in the room for a moment. Then, Miss Holly pulled some string and a round measurements. Let’s lift the blinds up for this.”

112 113 Miss Holly went to the western window and pulled the string that lifted the blinds. Acronis started lifting the blinds on the southern window. It overlooked Hyperbola Road, a street leading from the main school building to Finley. Acronis spotted Abangu, who was walking slowly along the pavement, bending under the weight of her sports bag full of things. The weather was clear and sunny. Acronis admired red roofs and green lawns that were so clearly visible from the window of the Physics classroom. Then her attention was drawn to the unfinished tennis court, located near Finley. Acronis saw a bulldozer crawling along the court, looking like a heavy black and yellow beetle. Here it stopped. Here it turned. Here it moved in the direction of Abangu — slowly, then faster and faster… “Can I have your phone, Miss Holly?” Acronis screamed. Stunned, Miss Holly gave Acronis her mobile phone. Acronis dialed the number of Johnny Macintosh, which she knew by heart. “Johnny-the-lighting is speaking,” she heard his cheerful voice. “Johnny, this is Acronis, are you at home?” Acronis shouted, rushing away from the classroom. “Yes, I’m at my dad’s…” “Please, come to Finley right now! You must stop the bulldozer!” Acronis breathlessly explained to him, racing down the steps. After making sure that Johnny heard her, Acronis threw the phone away, jumped out into the street and rushed to Finley. ±

114 CHAPTER 24 THE CHASE

Abangu noticed the bulldozer moving towards her, when there was no more than a dozen of steps to the dormitory porch. For a moment she hesitated. It was too late to run forward. Abangu rushed back to school. There was a long narrow street between two rows of old houses in front of her. Abangu was scared. She was running away from the huge bulldozer, which was roaring behind her, with her heavy bag dangling on her shoulder. “Throw the bag away!” Acronis shouted, rushing along Hyperbola Road to Abangu. Abangu threw her bag off her shoulder and ran faster. Acronis saw the monstrous bulldozer flatten Abangu’s bag. A second later the girls met in the middle of the street. Acronis grabbed Abangu’s hand, and together they rushed to the door of the school. The bulldozer was rumbling behind them. To open the school door, one had to press their finger to the sensor screen on the wall. Breathless, Acronis reached the door and touched the sensor with her index finger. There was no click. Acronis pressed her fingertips over the sensor screen again and again, but the lock did not even think to open. “You try!” exclaimed Acronis to Abangu, but the girl, frozen by fear, was glaring at the blade of the approaching bulldozer. Then Acronis pulled Abangu, and both girls rushed in the direction of the lawn, which was separated from Hyperbola Road by two broad stone steps. The bulldozer followed them. Somehow Acronis and Abangu managed to jump out onto the lawn. Now they had an advantage of a few meters: the bulldozer stopped for a moment to cross the steps to enter the lawn. Acronis hoped to

117 take cover behind an oak tree — the one under which she had chatted with Shelly a few days ago. But then something unexpected happened: Abangu suddenly screamed and rolled on the grass. “What’s the matter?” Acronis yelled. “My leg!” Abangu yelled back. “I can’t! I can’t get up!” Meanwhile, the bulldozer already reached the lawn and was roaring at the girls. The next moments passed in slow motion for Acronis. She saw herself taking Abangu and trying to lift her on her back. She saw Abangu, embracing Acronis by the neck, making a pair of desperate jumps on one leg. She heard Mrs. Jellicoe’s voice: “Shoot, Barrow, what are you thinking about?” She saw how a red sports car flew out onto the lacrosse pitch, spreading out on the opposite side of the stream. She saw Abangu, slipping on the grass, pale from pain, under the blade of the bulldozer. What Acronis couldn’t remember later was where Mr. Paul had come from. Her memory kept the feeling of joy that Abangu was safe. Mr. Paul grabbed her in his arms and, dodging the heavy blade, ran off to the side, on the edge of the lawn. Suddenly, the slow-motion film ended. The light was shielded by a multi ton bulldozer. Just thinking about the approaching bulldozer’s blade, Acronis jumped. Perhaps it was the longest jump in her life. Having flown past the oak, she collapsed right into the stream. She could not stay on her feet, rolled forward and to the side, tried to land on her hands, and finally flopped into the cold clear water, breaking her right elbow on the stone. In the first seconds after the fall, while not yet feeling pain in her arm, Acronis turned her head to the lawn. Something unusual was happening there. A small red Ferrari appeared on the huge lacrosse pitch and crossed it within a few seconds. Instead of braking in front of the stream, Ferrari flew up towards it at full speed, made a dazzling leap and slammed into the left side of the bulldozer. There was a deafening chime and gnash. Glass splashed in all directions. Smoke poured down. The motor of the bulldozer stopped rumbling, but it did not become quieter: the howling of sirens, shouting, a metal ringing — the whole avalanche of sounds stunned Acronis. Only a minute later, she began to hear her own rather plain voice. Now her right arm really hurt. “Somebody, help Johnny!” Acronis screamed. “Get him out of the car!” But Johnny suddenly appeared in front of her: in blood and soot, but, as always, cheerful and smiling. “Do you want to spend the whole day in this puddle?” he asked. √ 118 CHAPTER 25 THE HOSPITAL

“A closed fracture of the ulna,” the doctor said, examining the X-ray image. Now we will put it in a plaster cast.” Acronis nodded in satisfaction. “So now I can’t play the harp?” she asked. “It will be difficult to do for three to four weeks,” the doctor confirmed. “You’d better think how you’re going to write with your left hand,” Mum mumbled. “Why?” Acronis became interested. “Is it difficult? At least, I’ll print my project papers on a computer with a binary code.” “You’ll stay at home for a week,” Mum announced. “You’ll come back to school when you’re able to wash and dress yourself.” “Will I?” Acronis asked. “Oh, great. I’ll see Doughnut then. But first I must talk to Chief Inspector Loring, Abangu, Miss Holly and Johnny.” “Sit still and do not move, please,” the doctor told her. “Otherwise, the plaster won’t set properly.” When the plaster finally hardened, Acronis swallowed another painkiller and went to see Abangu, who was already sitting in the hospital emergency room waiting for her. Abangu’s left leg was bandaged. An aluminum crutch stood beside her chair. “What did they tell you?” Acronis asked.

121 “Dislocation of the ankle joint,” Abangu said indifferently. Then, she continued in a completely military. Unfortunately, the operation was soon over. The military were ambushed and suffered different, agitated tone, “Listen, Acronis, I have to tell you everything! Sit down beside me.” heavy losses. Dad said that some information leaked. Mum changed all the ciphers of diplomatic “Wait a minute, please,” Acronis asked, looking questioningly at Mum. correspondence, but it was too late: the surviving terrorists decided to take revenge on Dad. One night, “You can chat a bit until Dad comes back,” Mum allowed. “He left the car in the ambulance at the gate of our embassy, someone wrote ‘Aruk Matan’ in red paint. The next morning somebody parking and it was dragged away by a tow truck.” was shooting at my dad. A bullet passed through the windscreen of his car just near his head.” Acronis sat next to Abangu. The girl took a deep breath and began to tell her story. “What about the police and the military?” “My dad’s a diplomat. When I was at primary school, we lived in the embassy quarter of Abuja. “Explosions began to rattle in the city at night,” Abangu said, without paying attention to Acronis’ It was really great there. The school I went to was also very good. Daughters of other diplomats question. “Dad strengthened the security of the embassy. Armed men were on duty in our garden studied there, together with several girls from Nigeria, including Naomi and Victoria. Naomi around the clock. Mum stopped taking me to school in the morning. It was Dad’s driver who drove and Victoria’s father, the oil minister, was a very important and powerful man. He was always me to school. There was a holster with a gun on his belt. This went on for several months.” surrounded by bodyguards. I didn’t really like Naomi after she accidentally hit me on the head “Weren’t you afraid?” Acronis asked. with a badminton racket. It was quite painful and the girls laughed at me. If it wasn’t for my mum, “At first I was, then I got used to it,” Abangu explained. “That summer, the city became quieter. I would have burst into tears, but Mum gave me an ice cream to make me feel better.” Television reports stated that international forces managed to expose a terrorist network. Dozens Acronis nodded and Abangu continued. of criminals were arrested. At that time, I was already finishing primary school. To mark the end “My mum also worked at the embassy. She was engaged in the transfer of encrypted messages.” of the school year, a big celebration was organized. At the concert I had to play the violin.” “How interesting!” Acronis said with admiration. “Can you play the violin?” Acronis did not believe it. “The embassy was surrounded by a high wall,” Abangu said. “We had a spacious garden with “Yes, it is my favorite instrument,” Abangu confirmed. “On the eve of the concert, Dad left a green lawn and a swimming pool. One day Mum and Dad were sitting on the swing in the for Somalia. His chauffeur took Mum and me to school and waited in the car. All the girls at the garden talking. I hid behind a palm tree and listened to them. They talked about a terrible sect, concert were wearing white shoes and white dresses. Many girls came there with their parents. Aruk Matan, which had captured Maiduguri and other cities in the north of Nigeria. Dad said Minister Murtalu, Naomi and Victoria’s father, was also there. He was sitting in the front row that someone in the Nigerian government was connected with the terrorists — that is why they and his bodyguards were standing near the door of the hall. I performed very well. Everyone was couldn’t be caught and the army couldn’t do anything about them. Mum said that some man clapping and cheering me, even the minister.” offered her money for showing him Dad’s letters. Dad got worried and asked her to be careful.” Abangu caught her breath. Acronis, feeling that the story was approaching the end, began to Acronis was listening with bated breath. sway in her chair with impatience. Finally, Abangu started speaking again. “A week after this conversation, Dad gathered a meeting at the embassy. Some people in “When the party was over, we went to our car. We were following the minister and his daughters, uniform arrived: two police officers and ambassadors of other states. I don’t know what they when suddenly two burly men wearing green robes and dark glasses grabbed my mum. They were talking about. The next day, international troops launched a military operation in the north threw her into the backseat of a big black car. One of them sat down next to her. He was holding of the country, and they managed to seize two terrorist camps.” her hands all the time. Another man got behind the steering wheel. The car moved.” “Was it your dad who commanded the operation?” Acronis asked. “What were you doing at this time?” Acronis asked. “Of course not,” Abangu answered. “My dad is not a military man. It seems to me that he only “I wanted to run after them, but Dad’s chauffeur grabbed my arm and didn’t let me go until managed to find out where the Aruk Matan camps were located and gave this information to the the black car was out of sight.”

122 123 “Did you cry?” “But I know what would have happened to my dad’s Ferrari,” Johnny said. “It wouldn’t have a “Of course, I did. My mum called for help, but no one helped her. Neither the minister, nor his single scratch and neither would I.” bodyguards, nor Dad’s chauffeur, nor other guests.” “You’re a real hero, Johnny!” Acronis sighed admiringly. “But why?” Acronis gasped. “You still don’t know all the details, do you?” Johnny continued enthusiastically. “When I was “They were all afraid of Aruk Matan,” Abangu explained. “And they’re still afraid.” driving to you through the fields and meadows, my car knocked down a sheep! Now the farmer’s “What happened next?” going to sue me.” “Dad came back the same evening. He already knew about everything. He said he wouldn’t “Mum, please buy this sheep from the farmer!” Acronis asked. “Dad will eat it with pleasure!” forgive the minister and that he would do his best to find Mum. He told me that I would go to Mum did not respond to this suggestion, as at that very moment her mobile rang and Dad study in England.” and Aeneas entered the room. They both simultaneously started talking very loudly. Johnny was “When did it happen?” Acronis asked. laughing whilst retelling the story about his Ferrari and the sheep. Dad, sitting next to Acronis, “Almost a year ago,” Abangu replied. “My dad and I agreed that he would send me letters every asked her about her arm. Mum was talking on the phone to Mr. Macintosh. three days. The most important letters about his search for Mum and Aruk Matan would be Abangu stood up quietly, took her crutch and left the room. encrypted. Dad explained to me how to use the book cipher. It is not difficult. Every month he sent me a few three-digit numbers. These were page numbers of the book, which I used to decipher the ∫ letters. I tore off a piece of paper with this code and kept it separately.” “Is anybody looking for your mother?” Acronis asked hopefully. “Yes, but I think she died,” Abangu said sadly. “Why?” Acronis exclaimed. “The terrorists said that they would release Mum only if Dad told them the names of the agents who gave him the information about the secret camps of Aruk Matan. Dad refused.” “Do you think they decided to get revenge?” “Yes, they did. I think they killed Mum. My dad thinks so too. He is very unhappy,” Abangu concluded sadly. “Please, tell me one more thing,” Acronis asked. “What happened two weeks ago? Why did you write ‘Aruk Matan’ on the floor?” Abangu wanted to say something, but the blue door opened and Johnny Macintosh entered the room. Both of his hands were bandaged, there was a sticking plaster on his cheek and a huge bruise under his left eye. “How are you feeling, young ladies?” he asked, smiling. “Oh, Johnny!” Acronis greeted him. “Happy to see you! I don’t know what would have happened to us if you hadn’t come.”

124 CHAPTER 26 THE WAVE FUNCTION

After the family dinner in a Japanese restaurant, Mum went to the Finley building to collect Acronis’ things. Aeneas drove Johnny to Macintosh Manor in Dad’s car. Dad and Acronis went to visit Miss Holly. Holding the plaster cast with her left hand and occasionally grimacing in pain, Acronis was walking along Hyperbola Road, remembering the recent dramatic events: there, Abangu saw the bulldozer; and there, she threw her bag. The remains of Abangu’s bag had already been removed. There was the place where Abangu and Acronis met and ran away together. Acronis looked at the school door and at the lawn. The school entrance was blocked by yellow ribbons. In the middle of the ruined lawn was a huge bulldozer and a wrecked Ferrari was resting next to it. Acronis put her finger on the sensor screen on the school wall. The lock clicked and the door opened. “Why didn’t it want to open before?” Acronis said aloud. “Maybe your hands were wet,” Dad suggested. “Or it was one of those fatal accidents that changed the history.” Miss Holly was waiting for them in the lobby. “I’m sorry, Miss Holly,” Acronis began. “It seems I have broken your phone!” “No worries, Acronis,” Miss Holly said. “Actually, it is me who has to apologize. It took me some time to understand what was going on. When I saw you rushing to school, all I could do was shout for help as loudly as possible. We are lucky that the Biology classroom is quite close and that Mr. Paul can run well.”

127 “Please, thank him on our behalf,” Dad said. “He was risking his life.” “Now imagine that Aeneas and you are simultaneously catching your dad by his hands. You, “Miss Holly,” Acronis started impatiently, “could you tell me what the quantum measurement is, Acronis, are grabbing your dad’s left hand. What hand is Aeneas grabbing then?” please? Without any magic wands and balloons. I’d like to know how it actually happens.” “The right one, of course!” Acronis could not understand what Miss Holly was getting at. “Very well, Acronis,” Miss Holly agreed. “Can we ask your dad to help me?” “Great. Now you know everything you need to understand how quantum measurements help to “What shall I do?” Dad seemed to be interested. transmit secret codes. Let’s suppose your Dad is an entangled state of two photons. Having caught “You’ll act as a wave function!” Miss Holly said. one of them in the ‘left hand’ position, you can be sure that another one (for which Aeneas was Dad smiled and took a pose of Admiral Nelson on the Trafalgar Column. hunting) is in the ‘right hand’ position.” “Look, Acronis,” Miss Holly began. “Each tiny quantum particle has a wave function which can “And what if Aeneas grabbed Dad’s leg?” be quite large. Like your dad, for example.” “It is possible,” Miss Holly said seriously. “Every time you catch your dad, Aeneas and you will “He’s losing weight, actually.” Acronis stood up for her dad. exchange information about which part of his body you’ve grabbed. For example, having caught his “Oh, sorry, I didn’t mean it,” Miss Holly was embarrassed. “I wanted to say that if I asked you left hand, you shout: ‘Hand!’. If Aeneas responds ‘Hand!’, you know for sure that he’s caught your where your dad was at the moment, you would immediately answer: “Here he is!” Right?” dad by his right hand. If Aeneas says: ‘Foot!’, it isn’t clear for you if he’s caught your dad by his right “Yes, I would,” Acronis nodded. or left foot. You can’t see it as your eyes are blindfolded.” “Now imagine that I asked where exactly he was? Where was his hand? His leg? His head? What “So what?” Acronis seemed to be a bit tired of this imaginary cat-and-mouse game. would you say?” “It means, Sunshine,” Dad joined the conversation, “that you and Aeneas will take into account “I would say that it was there, and there, and here.” only those cases when you managed to catch me by the same parts of my body. You will designate “Perfect!” Miss Holly was delighted. “Of course, your dad is at the same time partly in the space the right hand or leg by number one, and the left hand or leg by zero. Aeneas will do the opposite: occupied by his leg, and partly where his head is. This is not surprising. If instead of your dad for him my right hand or leg will be zero, and the left hand or leg will be one. By repeating this we were studying a quantum particle, for example a photon, the same thing could be said about game a hundred times, each of you will have a sequence of about fifty zeros and ones. These two it: it is here and there, in this state, or in the other. The states of a photon, as you remember, are sequences will be exactly the same. So, this will be your key to the cipher.” characterized by color, phase and polarisation.” “And what if someone else is catching you at the same time?” Acronis asked. “Sorry, Miss Holly,” Acronis interrupted. “I don’t quite understand. Do you want to say that a “They won’t succeed,” Dad replied, “because by grabbing my hand, this person will exclude the photon has different colours at the same time?” possibility of my hand being caught by you or Aeneas. There are only two hands!” “Exactly,” Miss Holly confirmed. “Colours, phases, and polarisation. You can say that it is likely “Phew!” Acronis said. “It’s difficult, but I think I’ve got it.” to be blue, but it may be red; however, when you make a measurement, you know for sure whether The doorbell rang. it is blue or red.” “This must be Mum and Aeneas,” Acronis guessed. “Thank you, Miss Holly!” “I don’t understand,” Acronis shook her head. “Thank you very much for not giving me the role of Schrödinger’s cat!” Dad smiled, and Miss “Well. If you, blindfolded, come into a room where your dad is silently dancing a Scottish jig,” Holly burst out laughing. Miss Holly explained, “you won’t be able to locate him until you catch him, but, having caught him, They were going back home late in the evening. Aeneas was driving. Acronis, leaning on her you’ll know for sure that he is where you’ve caught him.” mum’s shoulder, was having a nap in the back seat. Her arm ached, so her dream turned out to be torn “That is clear,” Acronis agreed. “So what?” and restless. Suddenly, the phone rang in Acronis’ pocket. She pulled it out and spoke in a sleepy voice:

128 129 “Acronis is speaking.” “Good evening, Acronis, this is Chief Inspector Loring,” a voice could be heard. “Good evening, Chief Inspector. How are you?” Acronis answered politely in a way that a good English girl from a private school would do. “I’m fine, thank you!” the Chief Inspector replied. “I’m sorry to bother you so late in the evening. On behalf of Scotland Yard, I just wanted to apologize for the danger that we failed to prevent. I can’t imagine what you and Abangu had to endure…” “No worries, Chief Inspector!” Acronis generously forgave him. “I wanted to tell you something very important.” ICTIONARY

“I’m listening to you, Acronis!” the Chief Inspector replied. D “Today Abangu told me that it was she who tore off the edge of one of her letters, on which the key for the cipher was written. She kept this piece of paper separately — not in the place where all her letters were kept. Do you understand what this means?” “I think I do,” the Chief Inspector confirmed, “though, I would be very grateful if you told me what conclusions you draw based on this information.” The wave Schrödinger’s cat “With pleasure!” Acronis exclaimed. She did not sound sleepy any longer; the girl felt vigorous function Was also created by Erwin Schrödinger. and confident. “The scrap of paper could’ve been stolen much earlier than the letters,” she explained. This imaginary cat is sitting in a box next “Abangu wouldn’t have needed it until she’d received a new encrypted letter. The criminal could have Was invented by Erwin to a flask of poison and a little hammer that Schrödinger in order can shatter the flask at any time. Nobody read her previous letters and then put them back — so as not to arouse suspicion.” to explain the mysterious “So?” the Chief Inspector became interested. knows when exactly it is going to happen. properties of atoms. This The hammer is triggered at the time “The thing is, that in the end, the criminal stole all the letters. It happened the night when Naomi function allows you to see of the decay of a radioactive quantum particle. and Victoria left Finley.” the probability of a quantum If an observer opens the box at a certain “You mean that…” particle being detected time, they will find the cat either dead or at a certain point in space. “The letters were stolen by Naomi and Victoria!” Acronis said in the tone of a prosecutor. “They alive with the same probability. The paradox wanted revenge on Abangu, who betrayed their secret. They couldn’t forgive the fact that they is, that, from the point of view of quantum had to move to another school. They had been reading Abangu’s letters for a long time and they physics, before the box is opened, the cat may simultaneously be both dead and alive. knew that Abangu’s dad was seeking the resignation of their father, Minister Murtalu. Naomi and Victoria never liked Abangu, but when she frightened them with a scary inscription and made them a target of journalists, Victoria and Naomi decided to take their revenge. They stole the letters and immediately handed them over to someone who had come to collect them that night; this person, who you have to find, gave all the information to Aruk Matan.”

130 Acronis stopped, waiting for objections from the Chief Inspector. He was silent. Acronis thought “Stop it, please! Stop it! I have a headache!” Mum tried to calm her down. But Acronis screamed that her phone was off. and cried until she choked on tears and coughed. Mum slapped her back with her hand. The cough “Chief Inspector Loring?” she asked. finally stopped and Acronis became quiet. “Yes, Acronis,” the Chief Inspector replied. “It sounds quite convincing. Well, it’s too late. I won’t “Mum and I wanted to tell you that we’re not going to divorce,” Dad said calmly. “Are we, darling?” distract you anymore today. I think we’ll have more time to talk when you’re back at school.” he asked and looked at Mum over his shoulder. “Chief Inspector,” Acronis did not want to give up, “may I ask you something else?” There was a long pause. Acronis held her breath. In about ten seconds, Mum said: “Of course, Acronis,” the Chief Inspector said. “Yes, dear, that’s true.” “Who were those people driving the bulldozer?” The car suddenly swayed sharply: first to the left and then to the right. “Extremely dangerous and terribly bad people,” the Chief Inspector replied. “We’ve been searching “What are you doing?” Mum asked Aeneas angrily. for one of them for six years. Thanks to you we have managed to catch him.” “I was driving around the pit”, he answered innocently. “Are they connected with Aruk Matan?” Acronis asked. “Possibly,” the Chief Inspector said evasively. He politely said goodbye and hung up the phone. ƒ Acronis was on cloud nine. Chief Inspector Loring liked her version and called it “quite convincing”. The old inspector was a bit restrained, as in fact it was the only possible version. All the pieces of the puzzle came together. All the spooky events of recent weeks could be explained now. Moreover, Abangu had been saved, the criminals arrested, and all this thanks to her, Acronis, Mr. Paul, Johnny, and Sergeant Barrow… Suddenly, for no apparent reason, Acronis recited a dialogue between Rosencrantz and Guildenstern: “On Fortune’s cap we are not the very button. Nor the soles of her shoe!” “Acronis,” Mum interrupted her. “Since you’re not sleeping and we’re all here together…” “What?” Acronis asked. “Dad and I wanted to tell you something. Aeneas already knows it.” The happiness Acronic felt instantly turned into hopeless despair. Her eyes filled with tears. Before Mum could say anything else, Acronis screamed: “No! No! No!” She beat her head against her mum’s shoulder, shook her dad’s seat with her healthy arm and cried: “I don’t want it! Oh, please! No! No!”

132 CHAPTER 27 VISITING SHELLY

The following weekend was free and the girls were allowed to go home. Shelly went to London. Her father and mother invited Acronis and her parents for Sunday lunch. Shelly’s mum, Mrs. Windfall, roasted a leg of lamb for the occasion. “Today, you will be cutting meat for our daughter, darling,” Mum said to Dad when he was trying to park his car in a narrow London street. “I’ve been doing it the whole week.” “With pleasure,” Dad said and turned off the engine. Everyone got out of the car. After climbing up the steps of a big Georgian house, Mum pressed the bell button. A second later, shining Shelly answered the door. “Come in! Feel yourself at home!” she greeted them. Mum and Dad stepped into a spacious hall and met Shelly’s parents. Shelly rushed towards Acronis and grabbed her hand. “Look who is our guest today!” she exclaimed. Abangu looked out from the kitchen door. She smiled at Acronis. Lunch was unbearably long. The parents talked about some boring things. Shelly’s mother was fussing over the plates. Acronis’ dad was telling Shelly’s father the story of how sheep destroyed the Spanish Kingdom. Acronis’ Mum was talking about Doughnut and his gastronomic preferences. Finally, after dessert, the girls were allowed to go and play in Shelly’s room. Abangu climbed the stairs, leaning on her crutch. The girls shut the door behind them and jumped onto Shelly’s bed.

135 “Well, tell me the news!” Acronis asked. Acronis and her parents were going back home in a very good mood. Dad was praising the leg Shelly, who was rather talkative, immediately shared all the school news with her. of lamb cooked by Mrs. Windfall. Mum, following her advice, joined a club of cat lovers. Acronis Carin won the swimming competition and she’ll be taking part in the English championship for felt absolutely happy. children. Rehearsals of Hamlet are in full swing. A new girl, Esme, who’s playing Polonius, is hiding “Oh, by the way,” Mum began when they were driving up to their house, “do you want to return behind the curtain in a very funny way and Marie-Rose can’t get at her with the dagger. Mr. Paul to your old school?” received a birthday cake in the form of a rat. The bulldozer and the Ferrari were removed from the “To my old school?” Acronis was surprised. “Why?” lawn, which is being put in order. Sergeant Barrow no longer comes at night but a police car drives “Shelly’s mum believes Dad and I need to spend more time with our children. At the moment to and fro along Hyperbola Road. Miss Parfitt handed over a box of chocolates for Acronis. The we can see you just once a week.” Enigma machine was taken back to the museum. “No, I don’t,” Acronis said. “I like my new school. Miss Holly is great, and Miss Parfitt, and Mr. When Shelly finished, Acronis asked Abangu: Paul, and the girls. Why don’t you sell this house and buy another one which is closer to the school? “Any news from your dad?” Then you could see me almost every day.” Abangu flushed and stammered. Then she muttered: “Ok, I’ll think what we can do,” Mum answered. “Everything’s OK. He’s coming soon. I’ll tell you later.” It was clear that Abangu did not want to say anything in front of Shelly. So, Acronis decided to γ go for a trick. “Shelly, where are the chocolates that Miss Parfitt has sent to me?” “In the kitchen,” Shelley replied. “Wait, I’ll fetch them now.” As soon as Shelly disappeared behind the door, Abangu moved closer to Acronis and whispered: “They’ve found my mum!” “Have they? Is she alive?” Acronis gasped. “She’s lost a lot of weight,” Abangu told Acronis. “Dad’s writing that it’ll take two or three weeks for her to recover. They’re going to come here when Mum is better.” “But where were they hiding her? In the jungle?” “No, in Abuja. In the basement of some house,” Abangu whispered hurriedly, looking at the door. “MI6 was able to decipher the Aruk Matan correspondence with the man who was chasing us on the bulldozer. They managed to hack the computers of the terrorists and found out where to look for mum.” “This is great!” Acronis managed to say before the door swung open and Shelly flew into the room with a box of chocolates. “Look, there is dark, white and milk chocolate!” she chattered. “Can we have some, Acronis?” Acronis allowed Shelly to open the box and the girls began to try chocolates.

136 CHAPTER 28 ENCRYPTED LETTERS

Several days later Acronis went back to school. Now she had fewer lessons. Instead of swimming, playing lacrosse and doing harp, she had free time. So, one day Acronis went to listen to Abangu playing the violin. She did not regret doing so — Abangu did really well. To Acronis’ surprise, she played difficult and sophisticated melodies easily. Her violin sounded free and confident. When returning with Abangu to their dormitory after class, Acronis started talking about the Aruk Matan inscription again. “Did you know that Naomi and Victoria were spying on you?” Acronis asked. “I guessed so,” Abangu nodded. “Someone rummaged in my things when I wasn’t in the room. These two girls were so rude. They knew what had happened to my mum, but they weren’t sympathetic at all. Later, my dad wrote that the Minister Murtalu was connected with Aruk Matan. It turned out that he shared with them some money from oil sales. Dad said that the minister was afraid of Aruk Matan and he couldn’t break it off with them. Last year, Murtalu sent his family abroad and was about to flee the country, but he didn’t manage to. Instead, he was arrested. When I heard about this, I wanted everyone to know that Naomi and Victoria’s father had been helping terrorists. I decided to warn everyone at school that Aruk Matan was there with us.” “Where did you keep the letters?” Acronis asked thoughtfully. “In the violin case,” Abangu said. “It wasn’t the safest place though — the case didn’t have a lock. Apparently, the girls had seen me putting the letters there. They would take them out and read them

139 while I wasn’t in the room. Then, they retold them to their father or some other people who were even worse than him.” “Why did you think that it was me who’d stolen the letters then?” asked Acronis, surprised. “Dad warned me that the danger would come from someone who had appeared in our school recently. Victoria and Naomi had been studying here since last year.” “I see,” Acronis nodded. “It’s good that the worst is over. When will your mum and dad come?” “Next week,” Abangu whispered, looking around to make sure no one was listening. “Mum’s feeling much better.” Acronis and Abangu came to the door of Finley. Mrs. Jellicoe was waiting for them on the steps. She had an unusual expression on her face, as if she felt ill at ease. “Acronis, go ahead,” Mrs. Jellicoe said, opening the door. “Abangu, you have to come with me”. Abangu, perplexed, looked at Acronis and meekly limped after Mrs. Jellicoe. Acronis went inside and immediately saw Miss Parfitt. There were tears in her eyes. “What happened, Miss Parfitt?” Acronis asked. Her heart sank. Did something happen with Mum or Dad? Did Aeneas have an accident at the races? “This morning some terrorists from Aruk Matan attacked the embassy quarter in Abuja,” Miss Parfitt said sadly. “I’m really sorry to tell you that, but you’ll find out anyway.” “Abangu’s parents?” Acronis gasped. “Yes,” Miss Parfitt sighed heavily. “Her mum and dad… They were both killed.” “Oh, dear! What will happen now?” Acronis thought. Þ

140 CHAPTER 29 THE SCHOOL BALL

On the day of the School Ball the weather was perfect. The cloudless sky was so bright that the spotlights, arranged around the perimeter of the lawn on Mrs. Jellicoe’s order, were not turned on until 9.00 p.m. A motley crowd of elegantly dressed parents filled the lawn. The melodious sounds of three harps were blended into the noise of merry talk. In a huge marquee, set on the bank of the stream, waiters wearing tuxedos were laying the tables. A charity auction was taking place under a large oak tree. Acronis and Shelly kept looking out from behind the oak tree, trying to see their parents in the crowd. Acronis’ dad, who had hardly managed to change his sports uniform for a tuxedo and a bow tie, eagerly drained his third glass of champagne. Shelly’s father, Mr. Windfall, looked at him with admiration. “I would never dare to take part in the London Marathon,” he admitted. “Actually, it is only frightening before your start,” Acronis’ dad explained cheerfully. “In fact, you can keep your own pace. Moreover, every five miles there are tents where you can get some food: fruit, crackers, chocolate…” “Dear, you are the only person who could manage to put on weight whilst running a marathon,” Acronis’ mum joined the conversation. “I don’t think I’ve put on too much weight,” Dad contradicted, “but it’s not so important, after all.” “Participation is much more important than winning!” Mrs. Windfall supported Acronis’ dad.

143 The sound of a gong coming from the marquee called the guests to take their seats at the table. “We’re leaving right after the first course, dear,” Acronis’ mum said. “Are we? But then we’ll miss the wild boar roast!” Dad complained. “It’s not good for you to eat too much after running the marathon. And I still need to collect papers for buying a house. Tomorrow in the morning we’re going to the lawyer.” “Have you decided to move closer to the school?” Mr. Windfall asked. “Yes, we have,” Mum nodded. “Now it is important that Acronis isn’t expelled, otherwise all my efforts will be wasted!”

At the other end of the lawn, Miss Holly came up to Acronis and Shelly. ICTIONARY

“Hiding?” she asked cheerfully. D “Just bored,” Shelly complained. “All the girls have already gone home and we have to wait for our parents.” “Come with me to the physics classroom,” Miss Holly suggested. “We’ll sit on the windowsill looking down at the ball from above.” Acronis and Shelly happily agreed. Climbing up the empty stairs to the fourth floor, they entered Miss Holly’s dark classroom. Acronis looked at the familiar prisms on the shelves, an old spectrograph, the portraits of Bohr, Einstein and Heisenberg on the walls. “I’ve read your project paper,” Miss Holly told her. “I’m very glad that you’ve understood Shor’s algorithm so well.” “Dad helped me,” Acronis admitted modestly. “Well done anyway!” Miss Holly praised her. “I’ve sent your project to my friends in Cambridge. I think when you grow up, you could do quantum physics or computer science.” “I’d like to work for MI6,” Acronis said. Shor’s algorithm “Well,” Miss Holly smiled, “knowledge of quantum physics will probably be of use if you become Is a way to decompose a large number into simple factors using a quantum computer. For very large numbers (consisting of, for example, several hundred characters), a secret agent.” the problem of decomposition into elementary factors is practically impossible Shelly was sitting on the windowsill swinging her legs, looking at the big white marquee on the to solve, even for the most powerful classical computer. This is the reason why secret lawn in front of the school. It was glowing from the inside with light shadows running along the information is often protected with the help of large numbers. Those who do not marquee’s surface. Miss Holly came up to Shelly. know a predetermined set of factors have very little chance of breaking through such “I’ve heard your parents want to adopt Abangu?” she asked. protection; however, for a quantum computer using Shor’s algorithm, the task is not “Yes, but this is rather difficult,” Shelly replied. “Every day, Dad goes to the Ministry of Foreign very complex. Affairs, then to the Ministry of Internal Affairs, trying to arrange necessary papers.”

144 “Is Abangu okay with it?” “Oh, Acronis, I’ve been waiting for you!” Miss Parfitt came out of the side door to the hall. “Hello, “Yes… In the beginning she didn’t want to, but then agreed. I think she is fine. Tomorrow we’re Aeneas!” she added, seeing that Acronis was not alone. meeting her at the airport.” “Good evening!” Aeneas greeted her back. “Is she flying from Somalia?” “I’m not offering you tea,” Miss Parfitt continued. “I know that you are in a hurry, but I have a “Yes, she went there with someone from their embassy. She had to go to the cemetery and then little something for you, Acronis. Please come to my office.” pick up some things from home. Abangu told us that she would never go back to Africa.” Acronis looked at Miss Parfitt in surprise. “What might it be?” she thought. “Hopefully, it isn’t Miss Holly and the girls fell silent. It was getting dark and the first lights shone in the windows some extra homework. It’s a holiday.” of the houses on Hyperbola Road. This July evening was warm and calm. “I’ll go and put the bag in the boot,” Aeneas said. “Goodbye, Miss Parfitt!” Suddenly, the telephone rang in Acronis’ pocket. When Miss Parfitt and Acronis entered the office, Miss Parfitt closed the door tightly behind her, “Is that you, Aeneas?” the girl asked. turned a key in the drawer and pulled out a sealed envelope with no address on it. “Who else could it be?” Aeneas answered. “Get down from your dovecote, I’m coming.” “Don’t open it until you arrive home, please,” she said sternly. “Are we leaving already? The ball isn’t over yet.” “Of course,” Acronis was stunned. She said goodbye to Miss Parfitt, ran out, climbed onto the “Dad’s tired after the marathon and six glasses of champagne, and Mum can’t think about Land Rover’s seat and slammed the door behind her. As soon as the car started moving, Acronis anything apart from buying a new house,” Aeneas explained. turned on the flashlight on her phone and, trembling with impatience, opened the envelope. She Quickly saying goodbye to Shelly and Miss Holly, Acronis ran down the stairs. Once outside, found two sheets of paper inside. Only a few words were written on each of them. The inscription she saw Dad and Mum coming out of the marquee. Acronis waved at them and ran towards them. on the first piece was made in a smooth, clear handwriting. Acronis read: “Welcome to the Circus!”. “Are you ready?” Mum asked her strictly. “Your pyjamas, the charger, summer homework, your And the signature: “C”. On the second page, the letters were bouncing, uneven — the author of the trainers?” letter was clearly in a hurry. Acronis read the note, did not believe it, then reread it again and again. “Everything’s packed,” Acronis assured her. “The bag is in the Finley building; we’ll fetch it on Thinking for a minute, she neatly folded both sheets, put them in the envelope and turned off the the way.” flashlight. The second letter read: “They are alive, everything is fine. Do not tell anybody. Abangu.” Aeneas came in Dad’s Land Rover. Everybody took their seats. Mum sat in the front, Dad and Acronis sat silently all the way home and smiled to herself in the dark. Acronis in the back. “Did you manage to run the marathon?” Acronis asked Dad. “Yes, I did.” Dad said proudly. “Six hours, twenty-five minutes.” “Why are you driving the car as though it’s a bulldozer?” Mum turned to Aeneas. “Be careful, p l e a s e .” THE END Aeneas professionally taxied to the porch of the Finley building. “Let’s go for the bag!” he called Acronis, jumping out of the car. Acronis went to the door and put her finger on the sensor screen. There was a click, Aeneas pulled the door and, together with Acronis, found himself in a brightly lit hall. A huge bag sat in the middle of it.

146 ABOUT THE AUTHOR

Alexey Kavokin, born in St. Petersburg in 1970, is a scientist in the fields of quantum physics and photonics. He is a Professor at the University of Southampton (the U.K.) and the Westlake University (China), Head of the Laboratory of Optics Spina at St. Petersburg State University (Russia), a Principal Investigator at the Russian Quantum Centre, and a Scientific Director of the Mediterranean Institute of Fundamental Physics (Italy). Since 2018, Alexey has been the Director of the International Center for Polaritonics at the Westlake University (China). Kavokin is world-renowned not only because of his significant scientific publications, but also as the author of a series of children books about a curious cat named Saladin that investigates various historical enigmas. In addition, he authored a trilogy titled “Man of Science” exploring the wonderful adventures of a group of physicists, “English fairy-tales”, “Italian fairy-tales”, and “Acronis Chronicles”, in which the red-haired girl named Acronis, the main character of this book, appears for the first time. Alexey’s books are full of adventures, extraordinary scientific paradoxes, and nice recipes. All difficult scientific concepts are explained in language clear enough for intellectually curious readers of any age.

149 ABOUT THE BOOK AND THE COMPANY

The main character of the book is a 12-year old girl with red pigtails named Acronis. Acronis is a fearless and restless girl from an English family. Her parents are in the process of a divorce and they send their daughter to one of the best private boarding schools in England, where she becomes immersed in an adventure involving encrypted letters and international terrorism from the very first day. In this book, the author explains to his readers in easily understandable language what a quantum computer is and how to solve an absolutely reliable cipher. The girl got her name from the company Acronis. Acronis sets the standard for cyber protection through its innovative backup, anti-ransomware, disaster recovery, storage, and enterprise file sync and share solutions. Acronis solutions deliver easy, efficient, and secure cyber protectionfor any environment. Acronis is not just a business. They’re a group of individuals that sharethe belief that knowledge should be available to all. Constant learning, creating, and protecting knowledge, and advancing technology are integral parts of Acronis’ company DNA. To create, spread, and protect knowledge the Acronis Cyber Foundation, established in 2018, initiated several educational projects: building and funding schools, research, and training programs in underserved communities around the world. Since books are a timeless, proven way of sharing knowledge, Acronis also publishes children’s educational books for little fans of technology and racing, which can be enjoyed by the entire family. To learn more about our projects and support the work of the Acronis Cyber Foundation, www.acronis.org. 151 Литературно-художественное издание Для чтения взрослыми детям Акронис и квантовый компьютер Художник Янина Гёрриссен

УДК821.112.2 ББК84 (4Гер) Ш 76 Шнайдер Л.

Ш 76 Конни у зубного врача / Лиана Шнайдер ; Пер. с нем. – М. : Альпина Паблишер, 2019. – [30] с. : ил. – (“Лучший друг – Конни”). ISBN 978-5-9614-2432-4 Бывает, что кариес появляется на зубах даже у самых ответственных малышей, которые чистят зубы каждый день. И тогда обя- зательно надо пойти к врачу, чтобы вылечить больной зуб. Вот и Конни отправляется с мамой к стоматологу. И хотя она здесь не первый раз, лечение зуба — волнительный процесс. Вместе с Конни ваш малыш убедится, что зубной врач — это совсем не страшно, и проверит, правильно ли он чистит зубы.

Все права защищены. Никакая часть этой книги не может быть воспроизведена в какой бы то ни было форме и какими бы то ни было средствами, включая размещение в сети интернет­ и в корпоративных сетях, а также запись в память ЭВМ для частного или публичного использования без письменного разреше- ния владельца авторских прав. По вопросу организации доступа к электронной библиотеке издательства обращайтесь по адресу [email protected]. ISBN 978-5-9614-7035-2 (Серия “Лучший друг – Конни”)

ISBN 978-5-9614-2432-4 (рус.) © Издание на русском языке, перевод, ISBN 978-3-5510-8700-3 (нем.) оформление. ООО “Альпина Паблишер”, 2019

Главный редактор Л. Богомаз Руководитель проекта М. Шалунова Корректор О. Улантикова

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